The 2009 ATP World Tour Finals (also known as the 2009 Barclays ATP World Tour Finals for sponsorship reasons) was held in London, United Kingdom between 22 November and 29 November 2009. It was the first time the O2 arena hosted the ATP World Tour Year-End Singles and Doubles Championships. The event was renamed from Tennis Masters Cup to ATP World Tour Finals following the rearrangement of the ATP Tour.

Finals

Singles

Nikolay Davydenko defeated Juan Martín del Potro, 6–3, 6–4 It was Davydenko's 5th title of the year and 19th of his career.

Doubles

Bob Bryan / Mike Bryan defeated Max Mirnyi / Andy Ram, 7–6(7–5), 6–3

Qualification Spots were awarded to the top seven players highest ranked single players in the world ranking and the top seven doubles teams in the 2009 ATP Doubles Race, with one spot reserved for Grand Slam champions who finish outside of the top 8, but within the Top 20 players or teams. As this did not happen, the final spot went to the next player or team in the top 8. Two additional players and teams were also in London as alternates in case of withdrawals.

Singles qualification SdPlayerPointsTourDate Qualified1 Roger Federer10150155 July 2009 2 Rafael Nadal92051719 May 20093 Novak Djokovic7910224 Andy Murray66301820 August 20095598521inj Andy Roddick44102020 October 20096 Nikolay Davydenko36302512 November 20097 Fernando Verdasco33002313 November 20098 Robin Söderling30002517 November 2009

On 19 May 2009 after reaching his 7th final of the year at the 2009 Mutua Madrileña Madrid Open, 2009 Australian Open champion Rafael Nadal of Spain was announced as the first qualifier.

Rafael Nadal began the year by winning his first Grand Slam on hardcourt at the Australian Open, defeating Roger Federer in the final 7–5, 3–6, 7–6, 3–6, 6–2, just after defeating Fernando Verdasco in a tournament record 5 hours 14 minutes battle in five sets. Following his Australian Open triumph he reached the final of the ABN AMRO World Tennis Tournament losing to Andy Murray. He then revenged his loss by defeating Murray in the final of BNP Paribas Open. He then won three straight titles at the Monte-Carlo Rolex Masters, the Internazionali BNL d'Italia and at the Barcelona Open Banco Sabadell. He then lost in his fourth straight final in the Mutua Madrileña Madrid Open to Federer. He was the four-time defending champion at Roland Garros and had a 31-match winning streak in Paris, broken with a surprise fourth round loss to No. 23-seeded Robin Söderling. He then missed Wimbledon becoming the first player since Ivanišević to not defend his title, and lost his no. 1 ranking to Federer. He then returned at the Rogers Masters but he did not reach a final until the Shanghai ATP Masters 1000 losing to Nikolay Davydenko. He also reached the semifinals of the US Open and the Western & Southern Financial Group Masters. Nadal has a 4–4 record at the championship and reached the semifinals in 2006 and 2007. This is his 3rd appearance

On 5 July – after the 2009 Wimbledon Championships – Roger Federer of Switzerland who won his 15th Slam at the tournament over Andy Roddick was announced as the second qualifier.

Roger Federer began the year with a loss to Rafael Nadal at the final of the Australian Open. He won his first title of the year at the Mutua Madrileña Madrid Open defeating Nadal in the final. For his first win over Nadal since 2007 and ending Nadal's 5 match winning streak. After Nadal's early exit, Federer snapped up the French Open, beating Robin Söderling 6–1, 7–6, 6–4 in the final to complete the career Grand Slam. At Wimbledon Federer defeated Andy Roddick in the final. It was the longest match in the final of Wimbledon in terms of games 5–7, 7–6, 7–6, 3–6, 16–14. Federer reclaimed the world no. 1 ranking and broke Pete Sampras's Grand Slam record with a 15th Grand Slam. He won his 4th title of the year at the Western & Southern Financial Group Masters defeating Novak Djokovic. He was also a runner-up at the US Open losing to Juan Martín del Potro and the Davidoff Swiss Indoors losing to Djokovic ending his 3-year run at the tournament. He also reached 4 semi-finals at the Internazionali BNL d'Italia, Sony Ericsson Open, BNP Paribas Open and the Qatar ExxonMobil Open. He has a 27–5 record in the championship having won it on 4 occasions in 2003, 2004, 2006 and 2007. This is his 8th appearance.

On 20 August – After his title in the 2009 Rogers Masters defeating Juan Martín del Potro, Andy Murray of Great Britain was announced as the third qualifier.

Andy Murray won six titles in the year, more than anyone else. With titles in the Qatar ExxonMobil Open, the ABN AMRO World Tennis Tournament, the Sony Ericsson Open. As well as at Queens, in the Rogers Cup and in the Open de Tenis Comunidad Valenciana defeating Mikhail Youzhny. He was also the runner up at the BNP Paribas Open. He missed the Asian Leg due to a wrist injury. At the slams he reached the semifinals for the first time at Wimbledon, as well as the quarterfinals of the French Open for the first time. This is his second appearance with a 3–1 record following his semifinal appearance last year.

On 10 September – Novak Djokovic of Serbia the defending champion was the Fourth to qualify following his third straight semifinal appearance at the 2009 US Open.

Novak Djokovic made his tennis do the talking as he won his first title of the year in Dubai Tennis Championships defeating David Ferrer. He then won three other titles in the inaugural Serbia Open defeating Łukasz Kubot, China Open defeating Marin Čilić and in Davidoff Swiss Indoors defeating Roger Federer. He then won his first Masters title of the year at the BNP Paribas Masters over Gaël Monfils. He finished as a runner-up at the Western & Southern Financial Group Masters, Gerry Weber Open, Internazionali BNL d'Italia, Monte-Carlo Rolex Masters and the Sony Ericsson Open. He also made the semifinal of the US Open. He is the Defending champion and has a 4–4 record. This is his 3rd appearance.

On 15 September – after his first Slam win at the 2009 US Open over Roger Federer, Juan Martín del Potro of Argentina became the fifth qualifier.

Juan Martín del Potro produced a break-out year, as he reached a career-high no. 5 and won his first Slam at the 2009 US Open defeating Roger Federer 3–6, 7–6, 4–6, 7–6, 6–2 in the final. He is also the tallest ever Grand Slam champion and the first player to defeat both Nadal and Federer in the same Grand Slam tournament. He also won two other titles at the Heineken Open defeating Sam Querrey, and the Legg Mason Tennis Classic defeating Andy Roddick. He also reached his first Masters final at the Rogers Cup losing to Andy Murray. He also reached the semi-finals at the French Open losing to Federer. Del Potro has a 1–2 record at the championship and is making his 2nd appearance.

On 20 September – despite an early exit at the US Open, Andy Roddick of the United States was the sixth qualifier.

Andy Roddick won the Regions Morgan Keegan Championships defeating Radek Štěpánek. His major triumph though came at the Wimbledon finishing as runner-up to Roger Federer. He defeated hometown hero Andy Murray and Lleyton Hewitt en route to this final. As well as finishing as a runner up at the Qatar ExxonMobil Open losing to Murray and the Legg Mason Tennis Classic losing to Juan Martín del Potro. At the Slams, he also reached the semifinals of the Australian Open losing to Federer after defeating Novak Djokovic. Plus making the fourth round of French Open for the first time, losing to Gaël Monfils. This is Andy seventh straight qualificationand his sixth appearance withdrawing in 2005. He has an 8–8 record reaching the semi-final in 2003, 2004, and 2007. Roddick withdrew from the tournament due to a left leg injury suffered at the Shanghai Masters.

On 12 November – After Verdasco fell to Čilić in the third round of the 2009 BNP Paribas Masters last years runner-up Nikolay Davydenko of Russia took one of the last two remaining spots.

Nikolay Davydenko won his first tournament at the International German Open defeating Paul-Henri Mathieu. The following week he won the ATP Studena Croatia Open Umag defeating Juan Carlos Ferrero. As well as the inaugural Proton Malaysian Open defeating Fernando Verdasco. Davydenko then claimed his 3rd Masters title at the Shanghai ATP Masters 1000 upsetting Rafael Nadal after defeating Novak Djokovic. He well as making the quarterfinals of French Open losing to Söderling. This is his fifth appearance with an 8–7 record. His best performance came last year as he reached the final losing to Novak Djokovic.

On 13 November after both Söderling and Tsonga fell to Djokovic and Nadal respectively in the quarterfinals of the 2009 BNP Paribas Masters Australian Open semifinalist Fernando Verdasco occupied the last remaining spot.

Fernando Verdasco started the year well with a semifinal appearance Australian Open losing to Rafael Nadal in a tournament record 5 hour 14 minute battle after five sets. He claimed his third title of his career in the Pilot Pen Tennis prevailing over Sam Querrey. He was also the runner up in the Brisbane International losing to Radek Štěpánek and the Malaysian Open losing to Nikolay Davydenko. Verdasco is making his debut at the championship.

After Roddick's withdrawal due to left leg injury on 17 November Robin Söderling was announced as his replacement.

Robin Söderling 's highlight of the year was reaching the French Open final. After becoming the first player to defeat Rafael Nadal at the Roland Garros. He won his only title of the year at the Catella Swedish Open defeating Juan Mónaco. He reached 4 semifinals as well at the Heineken Open, Proton Malaysian Open, China Open, and the If Stockholm Open. Soderling is making his debut at the event.

The two alternate spots were up for grabs. With the first one was taken by Jo-Wilfried Tsonga who won 3 titles including the SA Tennis Open defeating Jérémy Chardy, the Open 13 defeating Michaël Llodra and at the AIG Japan Open Tennis Championships defeating Mikhail Youzhny. His highlight at the slams was the quarterfinals of the Australian Open losing to Fernando Verdasco. The second spot was taken by Fernando González, who won the 2009 Movistar Open over José Acasuso 6–1 6–3. As well as reaching the semifinals of the French Open losing to Robin Söderling.

Doubles qualification RkPlayerPointsTourDate Qualified1 Daniel Nestor Nenad Zimonjić10510245 July 20092 Bob Bryan Mike Bryan9680245 July 20093 Mahesh Bhupathi Mark Knowles5950194 Lukáš Dlouhý Leander Paes5740155 František Čermák Michal Mertiňák3670326 Łukasz Kubot Oliver Marach3660229 November 20097 Max Mirnyi Andy Ram3550158 Marcin Matkowski33352613 November 2009 The first two teams qualified for the year-end doubles tournament on 5 July. They were the defending champions Daniel Nestor of Canada and Nenad Zimonjić of Serbia and the American brother duo of Bob Bryan and Mike Bryan from the United States following their doubles final at the 2009 Wimbledon.