Northern Ireland's McIlory becomes the seventh different No. 1 overall seed in the 15-year history of the Accenture Match Play Championship, and he will face the Ireland's Shane Lowry in the first round. Woods (USA) is back in the top four at the Accenture Match Play Championship for the 11th time after a brief absence (he was No. 19 last year) and will face fellow American Charles Howell III. England's Donald, the No. 1 seed a year ago, will face Marcel Siem of Germany in the first round; and Oosthuizen (SAF), who moved to No. 5 in the World Ranking today, rounds out the top four due to Brandt Snedeker's withdrawal with a rib injury; Oosthuizen will take on Scotland's Richie Ramsay.

Now that the brackets have been released, in the event a player withdraws from the Accenture Match Play Championship, the next player on the alternate list takes his place in the bracket. The next two players in the Official World Golf Ranking (as of Feb. 11 when the field was finalized) are: Bernd Wiesberger of Austria and Anders Hansen of Denmark.

Rory McIlroy -- No. 1 seed in the Bobby Jones Bracket; faces Shane Lowry in the first round

McIlroy joins Luke Donald (2012), Lee Westwood (2011), Steve Stricker (2010), Tiger Woods (1999, 2000, 2002-04, 2006-09), Vijay Singh (2005) and Ernie Els (2001) as No. 1 seeds in Accenture Match Play Championship history.

Making his 16th start in a World Golf Championships event, McIlroy has 10 top-10 finishes. The closest he came to winning was last year's runner-up at the Accenture Match Play Championship, losing to Hunter Mahan in the championship match, 2 and 1. This is McIlroy's fifth time competing in the Accenture Match Play Championship, a tournament where he made his professional U.S. debut in 2009. He has a 10-4 record and has advanced beyond the first round in each of his four previous appearances.

McIlroy is kicking off his PGA TOUR season at the Accenture Match Play Championship. He's made one start on the European Tour thus far, resulting in a missed cut at the Abu Dhabi HSBC Golf Championship.

Tiger Woods -- No. 1 seed in the Gary Player Bracket; faces Charles Howell III in first round

With a victory at the Farmers Insurance Open already under his belt in 2013, Woods returns to the Accenture Match Play Championship as a three-time winner of the event (2003, 2004, 2008). Woods has dominated the World Golf Championships with 16 wins in his career and holds the Accenture Match Play Championship record for both matches played (42) and matches won (33), as well as most appearances in the finals (4). He won a tournament record 13 consecutive matches from 2003-05.

In 12 previous appearances, Woods has only lost in the first round twice; however, he has not advanced beyond the second round since his win in 2008.

Luke Donald -- No. 1 seed in the Sam Snead Bracket; faces Marcel Siem in the first round

In winning the 2011 Accenture Match Play Championship, Donald never trailed in any of his six matches, and he joined Tiger Woods (2003) as the only players to win the Accenture Match Play Championship without playing the 18th hole.

Donald holds a 16-7 record at the Accenture Match Play Championship in eight starts. Last year, he became only the fourth defending champion to be eliminated in the first round (was defeated by Ernie Els, 5 and 4). Ian Poulter (2011), Steve Stricker (2002) and Jeff Maggert (2000) are the other three.

Donald made his PGA TOUR debut last week at the Northern Trust Open, where he finished T16.

Louis Oosthuizen -- No. 1 seed in the Ben Hogan Bracket; faces Richie Ramsay in the first round

Oothuizen moved to No. 5 in the Official World Golf Ranking today, passing Justin Rose (ENG) and taking the No. 1 seed in the Ben Hogan Bracket due to Snedeker's withdrawal. Oosthuizen is making his fourth Accenture Match Play Championship appearance and will be looking to improve upon his 1-3 record. Last year was the first time he advanced beyond the first round before losing to Stricker on the 18th hole in round two.

In his three previous appearances, Oosthuizen has entered the event seeded 49th in 2009, 20th in 2011 and 28th in 2012.

Like McIlory, Oosthuizen is making the Accenture Match Play Championship his first PGA TOUR start of the season. In January on the European Tour, Oosthuizen won the Volvo Golf Champions and finished T34 at the Commercial Bank Qatar Masters.