In sunny, calm conditions at TPC Craig Ranch, Stiles 5-wood shot from 242 yards hit the pin on the par-5 18th to set up the short eagle try. Seventh on the money list with $303,427, hes already guaranteed a PGA Tour spot next year.
Osborn, 40th on the money list with only the final top 25 earning 2009 PGA Tour cards, had a 65 to match Stiles at 11-under 141.
Colt Knost, the 2007 U.S. Amateur champion from SMU, was 9 under after a 66.
I havent been nervous in a long time, but I was nervous on the first tee the last two days, but I want to do well in front of these people so badly, Knost said.
Fort Worth native Hunter Haas, 26th on the money list, shot a 66 to join Bryce Molder (67), Marc Leishman (67) and Jeff Klauk (69) at 8 under.
Im very happy with where I am right now, but when you lose focus and start looking at what others are doing, thats when you start to fold, Haas said.
Casey Wittenberg shot a 64, the best round of the day, to top a group at 7 under.
Stiles eagle turned an average round into a very good one. After shooting 4-under 32 on the front nine, he had a double bogey on the 12th hole and a bogey out of the bunker on par-4 16th. But after picking up two shots on the final hole, he finished where he started the day, on top of the leaderboard.
Thats two days in a row, Ive made my best swings on the 18th hole, Stiles said.
Osborn has missed more cuts this year (11) than hes had top-25 finishes (9) and came into this week having missed four cuts in his last six tournaments.
I got real lucky several times and had some good breaks, Osborn said.
One of those came on the par-4 eighth where his second shot was headed for the greenside rough, but hit a womens ankle and bounced back toward the green.
I gave her ball on that hole. She deserves all the credit for that par, he said.