By Ben Everill

NORTON, Massachusetts (Reuters) - World number one Rory McIlroy clinched his fifth PGA Tour title, and second in three starts, with a one-shot victory over South Africa's Louis Oosthuizen at the Deutsche Bank Championship on Monday.

McIlroy, who began the round three shots back of Oosthuizen, fired a four-under 67 in the final round for a 20-under 264 that handed the 23-year-old Northern Irishman the second of the PGA Tour's four FedExCup playoff events.

Oosthuizen (71), who trailed McIlroy by three shots with six holes to play at the TPC Boston, finished alone in second while former world number on Tiger Woods (66) was alone in third a further shot back.

The win was McIlroy's third of the season and first since the last month's PGA Championship and put him level with Woods for the most wins on the PGA Tour this season.

(Editing by Frank Pingue)