The 2005–06 European football season was the 102nd season of Sport Lisboa e Benfica's existence and the club's 72nd consecutive season in the top flight of Portuguese football. The season ran from 1 July 2005 to 30 June 2006; Benfica competed domestically in the Primeira Liga and the Taça de Portugal and also participated in the UEFA Champions League as a result of finishing first in the Primeira Liga the previous season.
After Giovanni Trapattoni led Benfica to their first league title in 11 years, he resigned for personal reasons. To replace him, the club hired Ronald Koeman, who was assisted by Bruins Slot and Fernando Chalana. Benfica remained highly active in the transfer market, signing and releasing over twelve players. Noticeable additions were Anderson, Léo and Nélson to the back four; Karagounis and Miccoli to the offence. The departures included Miguel, the biggest loss.
Benfica started the domestic season by winning their fourth Supertaça Cândido de Oliveira, beating Vitória de Setúbal one-nil. In the Primeira Liga, Benfica struggled initially, making their worst entry ever. Results improved following a European win against Lille, with Benfica climbing several places and defeating Porto in the Clássico. In late October, the team experienced a drop in form, going a month without a win. In December, Benfica's results improved in December, qualifying for the knockout stages of the UEFA Champions League for the first time in eleven years and winning nearly ten matches in a row, allowing them to get within three points of the top of the league.
In the final match of January, Benfica lost to Sporting CP and underwent another erratic period, losing two more league matches in February. A home win against Liverpool motivated them; they beat Porto and eliminated the reigning title-holders from the Champions League. This success was not replicated domestically; in mid-March, Benfica lost further ground in the Primeira Liga and were eliminated from the Portuguese Cup. Koeman's side recovered, but they were eliminated by Barcelona from the Champions League and failed to overtake Sporting when they dropped seven points in three match-days. At the end of the season, Koeman left the club by mutual consent.
Season summary
Pre-season After leading Benfica to their first league title in ten seasons, Giovanni Trapattoni departed the club for personal reasons. Faced with the task of finding a new manager for a second year in a row, Luís Filipe Vieira was quick to choose Trapattoni's successor; on the 5 June 2005, he said, "I already know who's the next manager". From the list of available managers, the press speculated on Paul Le Guen, Ronald Koeman and Javier Irureta. After a failed approach to Le Guen, Benfica selected Koeman as the next manager on 8 June 2005. His assistant would be Tonny Bruins Slot, replacing Álvaro Magalhães, who left the club after two seasons. Later in the month, Fernando Chalana returned to Benfica on a 2-year contract to serve on Koeman's technical staff.
To replace the "Italian" style of Trapattoni, Koeman wanted Benfica to have a "Dutch" approach; he said, "A team like Benfica always has to play to win. In what I know of this team, we can perfectly play in a 4–3–3," and that finding the right balance between offence and defence in the playing style mattered. Vital to his new formation, Koeman asked for more wingers, such as Andy van der Meyde, and Boudewijn Zenden, but Benfica did not sign them. Instead, he received attacking midfielders Diego Souza, Andrei Karyaka and Giorgos Karagounis. To improve Koeman's options up-front, composed of Nuno Gomes and Mantorras, Benfica tried but failed to sign Jon Dahl Tomasson. Koeman instead received Italian international Fabrizio Miccoli on loan from Juventus. In defence, Benfica added Brazilians Anderson, Léo, with Nélson replacing Miguel, who moved to Valencia.
The pre-season began on 4 July 2005 with medical exams, followed by the first training session on the next day, with two thousand supporters present at the Estádio da Luz. On 6 July, Benfica travelled to Nyon for a pre-season tour until 14 July. During the eight days in Switzerland, Benfica defeated Sion and Étoile Carouge. Back in Portugal, Benfica faced two Premier League opponents, losing to Chelsea, and defeating West Bromwich. Afterwards, Benfica played three Portuguese teams, winning against Barreirense and Estoril Praia, and drawing with Vitória de Guimarães. They ended their pre-season with a presentation match against Juventus on 6 August, losing 2–0.
August–September Benfica began their season with the 2005 Super Cup, trying to win the trophy for the fourth time. On the 13 August, Benfica faced Vitória de Setúbal at the Estádio Algarve, winning 1–0 with a goal from Nuno Gomes. It was the first win in 15 years since 1989, breaking a five-time losing streak, all against Porto. Koeman praised his players, saying, "We played very well. I am happy with the work I have done with my players". On 20 August, Benfica began their title defence with an away game at the Estádio Cidade de Coimbra. The home team, Académica, held the score to 0–0 and won a point against Benfica. After the match, Koeman said Benfica had struggled in Coimbra. On 26 August, Benfica took part in the draw for the group stage of the 2005–06 UEFA Champions League; their first in the new century because they failed to qualify in the past two seasons. In 2005 the club ranked 57th in the UEFA coefficient, thus placing them on pot 4. They were drawn in Group D with Manchester United, Villarreal and Lille. The following day, Benfica hosted Gil Vicente for their final match in August. An unusual 3–4–3 formation did not work as planned; Benfica lost 2–0 and posted their worst league start since 1976–77. Koeman blamed anxiety in the players after Simão missed a penalty.
After an international break of nearly two weeks, Benfica returned to competition on 10 September with a Lisbon derby against Sporting CP. Koeman played the same 3–4–3 as before, selecting Carlitos for the starting 11 in place of Nuno Gomes. Sporting scored first through Luís Loureiro in the first half, but Simão equalized with a free-kick in the second half. In the 75th minute, Liédson made the score 2–1 against a ten-man Benfica, ultimately winning the match for Sporting. With two losses and a draw in three match-days, Koeman broke a club record for the worst season start in history, already eight points from the top of the league. Four days later, Benfica made their seasonal European debut in the Champions League against Lille. The match was well fought between both teams, with Fabrizio Miccoli scoring a winning goal for Benfica in the 92nd minute. Koeman later said in the post-match interview, "We deserved this win because we search for it". On 18 September, Benfica hosted União de Leiria; Koeman reverted to the 4–2–3–1 formation that Giovanni Trapattoni regularly used. Benfica won 4–0 in the largest win all season, with Nuno Gomes netting a hat-trick. Koeman classified the formation as "ideal," and sid he wanted to use it more often in the future. The following Saturday, Benfica played on the road against Penafiel. A strong start put Benfica in the lead by 2–0 in the first 15 minutes, and despite conceding a goal, they won the match 3–1. Koeman attributed the win to the good momentum that Fabrizio Miccoli–Nuno Gomes were passing. On 27 September, Benfica travelled to Old Trafford to play Manchester United on the second match-day of the Champions League. United scored first through a Ryan Giggs free-kick that deflected off the wall; Simão levelled the score in the second half—also on a free kick—but United responded with a winning goal in the 85th minute through Ruud van Nistelrooy.
October–November October began with a home match against Vitória de Guimarães. Miccoli opened the scoring for Benfica in the 20th minute, but Tiago Targino equalized a few minutes later. Simão put Benfica back in front with a deflected shot that beat Márcio Paiva, ensuring a third consecutive win that reduced the distance to the league leader to four points. After another interruption for international football, Benfica returned to competition with a Clássico against Porto. Despite Porto being the favourite to win, Benfica won 2–0 with two goals from Nuno Gomes. It was Benfica's first away win at Porto since 1990–91, when César Brito also scored a double. On the following Thursday, Benfica visited El Madrigal to play Villarreal. On the half-hour mark, Benfica lost their goalkeeper Quim to injury and replaced him with the 19-year-old Rui Nereu. In the second half, Villarreal scored from the penalty spot. Five minutes later, Manuel Fernandes levelled the score again. The draw allowed Benfica to remain in second place in Group D; Koeman was confident he could beat the Spaniards at home. On 22 October, Benfica hosted Estrela da Amadora for the Primeira Liga. Two second-half goals by Karyaka and then Nuno Gomes, gave Benfica their fifth consecutive win in the competition. Four days later, Benfica made their Portuguese Cup debut in the fourth round. Playing in Estádio do Bessa against Leixões, Simão's decisive performance opened the scoring in the 11th minute and scored Benfica's second goal that made the score 2–1. The month ended with an away match against Naval. Benfica were surprised by the home side and dropped two points in a 1–1 draw, costing them the chance to reach second place. Koeman was unhappy with the result, saying Benfica played better and deserved to win.
Benfica began November with a home match against to Villarreal. Benfica were hoping to win and take the lead in Group D but were defeated 1–0 with a winning goal for Villarreal in the 81st minute through a strike from Marcos Senna. Despite the loss, Koeman remained confident in the qualification for the knockout stage; he said, "It is a very balanced group. We are missing four points to progress." On 6 November, Benfica played Rio Ave at home. The match was unusually competitive, with Benfica trailing twice and avoiding defeat with two free kicks from Petit. Koeman took the blame but criticized the referee's assistant for making several mistakes against Benfica. After a third international break, Benfica visited the Municipal de Braga on 19 November to play Braga. Benfica scored first through Anderson but could not prevent the comeback of Braga, first through Césinha and then Julio Bevacqua. Benfica responded with a Nuno Gomes goal in the 92nd minute, but Bevacqua gave the win to Braga three minutes later. It was Benfica's fourth consecutive winless game, the worst spell of the season. Three days later, Benfica played Lille on the road for match-day five of the group stage. Koeman surprised with a highly defensive team composed of four centre-backs in the back-four, two defensive midfielders, two fullbacks playing in the midfield and only two offensive players, Miccoli and Nuno Gomes. The match ended 0–0, achieving Koeman's goal of securing a point. For the final game of the month, Benfica received Belenenses on 27 November. They were unable to beat Belenenses' keeper, dropping two points in a 0–0 draw and extending their winless run to six matches, the longest dry spell since 2001–02.
December–January