Mickelson, who began the day in a tie for eighth place with 17 points, struggled with five bogeys and one birdie in the third round to drop out of serious contention.
The world's fourth-ranked player regrouped in the final round, earning nine points to finish in a tie for 10th with 23 points.
Mickelson's final round of seven birdies and five bogeys included a string of four straight birdies from holes 8 through 11. In the end, though, it might have been the 21 putts he missed from 10 feet or shorter that did him in.
Either way, he said he's feeling good going into next week's PGA Championship. Mickelson has been slumping since he won three tournaments, all before the Masters.
``This was a great way to get some rust off, and there was some rust out there this week,'' Mickelson said.
GOOSEN AND GORE
Retief Goosen and Jason Gore, who melted down together in the final round of the U.S. Open two months ago, each managed to pick up victories Sunday.
Goosen came from behind to win the International a few hours after Gore won a two-hole playoff with Roger Tambellini to grab the hardware at the Nationwide Tours Cox Classic in Omaha, Neb.
The win was Gore's third straight on the Nationwide Tour, which makes him exempt on the PGA Tour through 2006.
Playing in the final pairing Sunday at the U.S. Open, Goosen finished with an 81 and Gore shot 84. Things got so bad that, just to keep things interesting, they wagered $5 on who would shoot lower over the final three holes. Goosen won the bet.
``That's great,'' Goosen said when told about Gore's big win. ``He's such a nice guy and a powerful player as well. Obviously, that bad round hasn't affected his game. It shows you he's got a good mental attitude, and that's what you need in this game.''
Carl Pettersson's final round was as up-and-down as the fairways at Castle Pines.
The Swede, who began his fourth round on the 10th hole, recorded just one par on his front nine and a total of four pars over the 18 holes.
``It was good in this format, and thank God I had some birdies in there,'' he said.
The fourth-year tour player's round included six birdies, seven bogeys and one double-bogey. He wound up in a tie for 15th with 21 points.
Pettersson's round included a stretch of 10 straight holes without a par, from the par-4 13th through the par-3 fourth.
The International is still without a repeat champion in its 20-year history.
Rod Pampling was the latest defending champ to go down.
The Aussie finished tied for sixth with 24 points.
Pampling, who had 15 first-round points en route to the title a year ago, started this year's event slowly, recording just 15 points over the first three rounds.
He climbed up the leaderboard thanks to nine points in the final round. Retief Goosen became the event's 18th different champion. Only Mickelson and Davis Love III have won more than once here.