Tin Cup by John Norville

Roy "Tin Cup" McAvoy is a former golf prodigy who has little ambition. He owns a driving range in West Texas, where he drinks and hangs out with his pal Romeo Posar and their friends. Dr. Molly Griswold, a clinical psychologist, wants a golf lesson. She asks Roy because he knows her boyfriend David Simms, a top professional golfer. Roy is immediately attracted, but she sees through his charm and resists.
Simms shows up at Roy's trailer ahead of a local benefit tournament. Roy thinks Simms is offering him an invitational spot to play, but Simms actually wants to hire him as a caddy (since Roy knows the course). During the round, Roy needles Simms about "laying up" instead of having the nerve to go for the green, 230 yards away over a water hazard. Simms fires back that Roy's problem is playing recklessly instead of playing the percentages. Roy brags that he could make it, and spectators make bets among themselves that Roy could. Simms warns Roy that he'll fire him if he tries, but Roy does anyway, hitting a brilliant shot onto the green. Simms immediately fires Roy as he said he would.
To get even, Roy decides to try to qualify for the U.S Open. He also makes a play for Molly, seeking her professional help. Molly agrees to help Roy rebuild his self-confidence in exchange for the golf lessons. In two qualifying rounds, with Romeo as caddy, Roy's golf is excellent but his head needs help. He continues to resist playing safely, smashing most of his clubs (leaving only his 7-iron intact) in a snit that causes Romeo to quit, but still manages to qualify. Following the round, he makes a wager with Simms that costs him his car. He persuades Romeo to go along as caddy, but develops a problem with his golf swing. On the first day of the tournament in North Carolina he shoots a horrible 83. Meanwhile, Molly gets a glimpse of Simms' unpleasant side when he arrogantly refuses to give a child an autograph.
Molly sees that trying to change Roy is a mistake and encourages him to be himself. At her suggestion, Roy wins another silly wager with Simms, the leader after the first round. Then with renewed confidence, "Tin Cup," a nobody from nowhere, shocks the golf world with a remarkable record second round of 62, making the cut. His third round is also excellent and moves him into contention. His flaw, though, is that on all three rounds, he refused to lay up on the par-5 18th hole, hitting the ball into the pond.
On the last day, Roy, Simms and real-life PGA Tour pro Peter Jacobsen are in a three-way battle to be the Open's Champion. Jacobsen finishes with a par on 18, tied for the lead with Roy and one shot ahead of Simms. Simms yet again lays up at the 18th hole, playing it safe, despite the fact that doing so takes him out of championship contention. Roy should do likewise to save par and force a playoff, but over Romeo's objections and urged by Molly to "go for it," he takes his fateful shot which finally carries the green. However, a "little gust from the Gods", a sudden contrary wind causes his ball to roll off the green and back into the pond. Reminiscent of his blow-up back in college when he failed to qualify for the Tour, Roy tries to hit the same shot repeatedly, with the same heart-breaking result. With one last ball in his bag, Roy risks not only being humiliated but being disqualified (having no golf balls to play with), but still goes for the green. On his 12th shot, the ball clears the water and slowly rolls into the hole. After a wild celebration, Roy finally realizes what he has done and feels ashamed of himself, but Molly assures him. "Five years from now nobody will remember who won or lost, but they're gonna remember your 12!"
Now back in Texas, Molly tells Roy that by finishing in the top 15 at the Open he automatically qualifies to play again next year. She further suggests that he go back to the qualifying school so he can get on the Tour. Molly, who picked up a bunch of new clients at the tournament, prepares for a career of helping players with the mental portion of the game. They kiss passionately as the movie ends.