Mahan turned professional in 2003 and made it through qualifying school to earn a
PGA Tour card for the 2004 season. His first PGA Tour victory, which came at the 2007
Travelers Championship, lifted Mahan into the top 100 of the
Official World Golf Rankings. In August 2007, Mahan entered the top 50 in the world rankings, and in that year finished 15th in the
FedEx Cup. His performances in 2007 saw U.S.
Presidents Cup captain
Jack Nicklaus choose Mahan as one of two captain's picks for the U.S. team. By March 2008 he had reached the top 30. On February 28, 2010, Mahan won his second PGA Tour event, beating fellow OSU golfer
Rickie Fowler by one stroke at the
Waste Management Phoenix Open. On August 8, 2010, Mahan won his third
PGA Tour title at the
WGC-Bridgestone Invitational. He beat
Ryan Palmer by 2 strokes. Mahan won his second WGC tournament in February 2012 at the
WGC-Accenture Match Play Championship. He defeated
Rory McIlroy, 2 and 1, in the final. Mahan recorded his fifth career PGA Tour victory in April at the
Shell Houston Open and moved to fourth in the
Official World Golf Ranking, making him the highest-ranked American for the first time. In defense of his title he won in 2012, Mahan reached the final of the
2013 WGC-Accenture Match Play Championship but was beaten 2&1 by
Matt Kuchar. In August 2014, Mahan won the first of the year's four FedEx Cup playoff events,
The Barclays. He won by two strokes from
Stuart Appleby,
Jason Day and
Cameron Tringale during a final round that saw six different players share the lead at some point. He birdied three of his last four holes to pull clear of the field. This was Mahan's first ever playoff victory and his sixth overall title on the
PGA Tour. Mahan was selected by
Tom Watson as one of his three captain's picks for the
2014 Ryder Cup team, finishing with a record of 1–2–1 in the four matches he participated in. This included a halved match against
Justin Rose in the singles competition. Mahan began struggling with his golf game as of the
2015–16 PGA Tour season, during the next four years, Mahan finished 183rd, 130th, 159th and 184th in the season-long FedEx Cup rankings and had to compete in the
Korn Ferry Tour Finals on multiple occasions to try to keep his full tour card. Between 2015–16 and 2020–21, Mahan had only one top-10 finish on the PGA Tour and 69 missed cuts. As of April 1, 2021, Mahan had fallen to 1738th in the Official World Golf Ranking. ==Personal life==