The first round of the 2011 U.S. Open at Congressional Country Club is in the books, and it was a banner day for Rory McIlroy, who fired a six-under 65 to put himself atop the U.S. Open leaderboard after Round 1. McIlroy had three straight birdies to get himself going and has a three-shot lead on the rest of the field.

There is a familiar contender lurking, though. Charl Schwartzel, who ended up as the 2011 Masters champion after McIlroy's final-day meltdown, finished strong with four birdies in his final nine holes to eventually finish at three-under. Schwartzel is tied for second place with Y.E. Yang, who set the early pace by firing a three-under in the morning.

Six players are right behind those two at two-under par, including Sergio Garcia, an accomplished pro who barely even qualified for the tournament. Twelve others, including defending champion Graeme McDowell are tied at one-under. Overall, 21 players shot under par on Day 1, compared to just 13 last year. There are still a few more stragglers on the course that could add to that number.

Here is a complete leaderboard of all the players under par:

1. Rory McIlroy: -6
2. Y.E. Yang: -3
3. Charl Schwartzel: -3
4. Ryan Palmer: -2
5. Sergio Garcia: -2
6. Scott Hend: -2
7. Alexandre Rocha: -2
8. Kyung-tae Kim: -2
9. Louis Oosthuizen: -2
10. Robert Rock: -1
11. Bubba Dickerson: -1
12. Davis Love III: -1
13. Chez Reavie: -1
14. Graeme McDowell: -1
15. Henrik Stenson: -1
16. Stewart Cink: -1
17. Robert Garrigus: -1
18. Brandt Snedeker: -1
19. John Senden: -1
20. Johan Edfors: -1
21. Alvaro Quiros: -1