Hale Irwin shot his age for the first time on the Champions Tour, finishing with a 6-under 65 for a share of the first-round lead in the AT&T Championship with 2007 and 2008 winner John Cook, Larry Nelson, Chien Soon Lu and Mark Wiebe.
"I don't know what you do to go and celebrate," Irwin said. "But whatever it is, I'll go and do it."
Mark Calcavecchia, Russ Cochran, Gene Jones, Chip Beck, Keith Fergus, Dan Forsman, Steve Lowery, Rod Spittle, Javier Sanchez and Kirk Hanefeld opened with 66s at Oak Hills Country Club.
Another 15 players were within four shots of the lead, including 2006 champion Fred Funk (68), 2005 winner Jay Haas (69) and defending champ Phil Blackmar (69).
The tournament is the Champions Tour's final full-field event of the year. The top 30 on the money list will advance to the season-ending Charles Schwab Cup Championship next week at Harding Park in San Francisco.
Irwin chipped in for eagle from just off the green at the par-5 15th and made a 9-foot putt to save par on the final hole. The tour's career victory leader is winless since 2007.
The 63-year-old Nelson missed a chance to match his age. Playing the front nine last, he bogeyed No. 8 and had a 10-footer for birdie No. 9 trickled off to the right.
"As most guys my age will tell you, to have three really good days in a row is difficult," Nelson said.
Cook had a bogey-free round. He has played 10 rounds at Oak Hills on the Champions Tour and has shot 65 or better half the time.
"Some places just fit you," Cook said. "This golf course just does."
Charles Schwab Cup points leader Bernhard Langer had a 69.
Kenny Perry, the 14-time Tour winner who is playing in his second Champions Tour event, had a 74. He tied for 35th last week at The Woodlands.