AUGUSTA, Mo. (AP) _ Gibby Gilbert said he was just trying to make up some lost ground when he suddenly realized he could win the tournament.

``I was two down with three holes to go and I thought `anything can happen now,''' Gilbert said Sunday after beating Hale Irwin on the first playoff hole to win the Senior PGA Tour's inaugural $1.2 million Boone Valley Classic.

Gilbert's 2-under-par 69 Sunday included a quadruple-bogey 8 on the 410-yard 2nd hole and was capped by a 6-foot birdie putt on the 401-yard 18th. He finished 54 holes at 10-under 203, tied with Irwin, who closed with a 70.

Gilbert said he was just trying to move up on the money list after hitting two balls in the water on his second hole.

``I was upset about how much that was going to cost me and I was just trying to get some of it back,'' Gilbert said.

He said he noticed that Irwin, who lives in nearby Frontenac, Mo., and had the gallery rooting for him at the 6,670-yard Boone Valley Golf Club, wasn't making any birdies.

``I made a good par on 16 and Hale bogeyed to cut his lead to one shot, and I thought anything could happen on the last two holes,'' Gilbert said.

Gilbert parred the playoff hole, the 18th, while Irwin was making a triple-bogey 7 after hitting his approach shot in the water.

``I just missed that shot, there's no big mystery about it. I hit a terrible 6-iron,'' Irwin said.

The victory was Gilbert's fifth as a senior and first since 1993. The winner's share of $180,000 was the largest paycheck of his career.

Irwin missed birdie putts of less than 15 feet on 11, 12 and 13. He birdied the 476-yard, par-5 14th after play resumed following a lightning delay, retaining his one-shot lead over Gilbert, who also birdied the hole.

``I wasn't playing to win, I was playing not to lose, and that's not my game,'' Irwin said. ``I kept everyone in the tournament with my poor putting.''

Irwin started the final round two shots behind Bunky Henry and one in front of Gilbert after a course-record 63 on Saturday. Irwin managed to par 18 to set up the playoff despite a poor drive that left him an awkward stance in the rough. Irwin hit his second shot over the lake to the back of the green and two-putted to tie Gilbert.

Henry, who came into the final round as a leader for the first time on the regular or senior tour, had a 73 and finished tied for third with Isao Aoki at 204.

Henry bogeyed the first hole and Irwin took the lead with a par on the 430-yard, par-4 5th, while Henry was making a bogey.

Aoki, who had a final-round 68, holed a 170-yard 6-iron for an eagle on 18.

Frank Conner and first-round leader Gary Player were at 205 after a 68 and a 70, respectively.