Matsuyama (a) 9. Winner of the 2010 U.S. Amateur Public Links Lion Kim (a) 10. Winner of the 2010 U.S. Mid-Amateur Nathan Smith (a) 11. The top 16 finishers and ties in the 2010 Masters Tournament Ricky Barnes, K. J. Choi (17,18,19), Miguel Ángel Jiménez (18,19), Jerry Kelly, Anthony Kim (15,18,19), Hunter Mahan (15,16,17,18,19), Steve Marino, Ryan Moore (17,18,19), Ian Poulter (18,19), David Toms, Nick Watney (15,16,17,18,19), Lee Westwood (13,16,18,19) 12. Top 8 finishers and ties in the 2010 U.S. Open Alex Čejka, Ernie Els (15,17,18,19), Grégory Havret, Dustin Johnson (15,16,17,18,19), Matt Kuchar (15,16,17,18,19), Davis Love III, Brandt Snedeker 13. Top 4 finishers and ties in the 2010 British Open Championship Paul Casey (15,17,18,19), Rory McIlroy (14,15,16,18,19) 14. Top 4 finishers and ties in the 2010 PGA Championship Bubba Watson (15,16,17,18,19) 15. Top 30 leaders on the 2010 PGA Tour official money earnings list Robert Allenby (17,18,19), Ben Crane (17,18,19), Jason Day (16,17,18,19), Luke Donald (16,17,18,19), Rickie Fowler (18,19), Jim Furyk (16,17,18,19), Retief Goosen (17,18,19), Bill Haas (19), Charley Hoffman (16,17), Jeff Overton (17), Ryan Palmer (17), Justin Rose (16,17,18,19), Adam Scott (16,17,18,19), Heath Slocum, Steve Stricker (16,17,18,19), Bo Van Pelt (17,18,19), Camilo Villegas (17,18,19) 16. Winners of PGA Tour events that award a full-point allocation for the season-ending Tour Championship, between the 2010 Masters Tournament and the 2011 Masters Tournament Stuart Appleby, Arjun Atwal, Aaron Baddeley, Jason Bohn, Jonathan Byrd, Martin Laird (17,18,19), Carl Pettersson, D. A. Points, Rory Sabbatini, Jhonattan Vegas, Mark Wilson (19), Gary Woodland 17. All players qualifying for the 2010 edition of The Tour Championship Kevin Na, Kevin Streelman 18. Top 50 on the final 2010 Official World Golf Rankings list Ross Fisher (19), Hiroyuki Fujita, Peter Hanson (19), Yuta Ikeda (19), Ryo Ishikawa (19), Robert Karlsson (19), Kim Kyung-tae (19), Edoardo Molinari (19), Francesco Molinari (19), Sean O'Hair, Álvaro Quirós (19), Charl Schwartzel (19) 19. Top 50 on the Official World Golf Rankings list on March 27, 2011 Anders Hansen 20. International invitees None Round summaries First round Thursday, April 7, 2011 Rory McIlroy and Álvaro Quirós shot 65 to co-lead after the first round. K. J. Choi and Y. E. Yang shot 67 to trail by two shots. Defending champion Phil Mickelson shot a 70 and Tiger Woods a 71. Henrik Stenson struggled to an 83, including a quintuple bogey 8 on the par-3 4th hole, the highest score on the hole in