Five months after answering those who questioned his resolve with a one-shot victory at the Masters, Phil Mickelson is facing the critics once again this week at the Ryder Cup at Oakland Hills Country Club.

Mickelson, whose Masters victory was his first major championship after many near-misses, caused a small stir in golf circles when he announced two weeks ago he was switching several elements of his equipment, including his ball. Some questioned why he would give himself so little time to adjust to the new gear before this week's biennial competition.

Even U.S. captain Hal Sutton said Tuesday that he was surprised by the timing, but Sutton maintained he was "not upset about it. I think anytime a great player like that makes a shift in equipment, I think everybody is surprised by it. You can't be upset about things like that because he's got a life that he's got to live. He's got things he has to answer to."

Mickelson insisted Wednesday morning that his move from a longtime relationship with Titleist to his new 10-year agreement with club and ball maker Callaway will only help him this week.

"Why would they question that?" Mickelson said. "I really don't know how to get into it, other than I feel that I am most confident my ability to score lowest is now. It's with the ball I'm playing and with the woods I'm playing. I didn't make a change with the irons because of exactly that concern, the distance controls and so forth. I had not had enough time to factor it in."

Mickelson will drive this week with a Callaway Great Big Bertha II and use the company's 3- and 4-woods, keeping his old Titleist irons in the bag for now. He's also switched to the Callaway HX Tour golf ball.

Most players generally make significant equipment changes in golf's offseason. Some do it for the endorsement money; others because they fall in love with the way a new club or a state-of-the-art putter feels in their hands, or the distance or better control they will get with a certain club or ball. Industry sources familiar with Mickelson's switch indicated all of the above reasons were involved in his decision. He also indicated he's hitting his new driver 15-25 yards longer when he wants to, without losing accuracy off the tee.

Mickelson's Masters victory made him even more marketable, but Titleist, which counts Ernie Els and Davis Love III among its roster of top stars, told Mickelson it was not prepared to give him a significant increase when his contract ran out this year.

Not long after the PGA Championship, Mickelson spent a day at Callaway's test center in Carlsbad, Calif., about 25 minutes from his home in Rancho Santa Fe, and said he became enamored with various clubs and balls he hit that day. Callaway reportedly has signed him to a 10-year deal, and while the company declined through a spokesman to offer any terms of the contract, another industry source indicated it was likely in the $8-million-a-year range.

There are plenty of sad stories about players switching club manufacturers and failing miserably. Corey Pavin did it the season after he won the 1995 U.S. Open at Shinnecock Hills, and went from $1.3 million in earnings that year to $99,000 two seasons later. Steve Stricker finished second in the '98 PGA Championship, changed clubs in the offseason and went from 13th on the money list that season to 113th two years later.

Mickelson raised more than a few eyebrows in his first tournament after the switches, last week's Canadian Open. He shot 75 in the first round, 69 in the second to make the cut, then had his worst score of the season, a 79 Saturday to go 10 over par after 54 holes. On Sunday, he came back with a 68 and tied for 57th, in a year when he's had 13 top 10 finishes in 19 starts, missing only one cut all season.

"Last week, it's tough to say because I had not had the time to prepare for the event," Mickelson said Wednesday. "I had a lot of stuff going on and didn't practice. But I had plenty of time [during the tournament] to practice. It was evident in my final round, and it's been evident to me early this week that my game is as sharp as it will be."

Mickelson took the day off from practice Wednesday, the only American to do so, because he told Sutton that's his normal routine before a major championship. Sutton said he had no problem with that decision because it indicated Mickelson was in the proper frame of mind to take this tournament just as seriously as a major.

The day before, Sutton had said he saw no discernible difference in Mickelson's form from earlier this season, when he also finished second by two strokes in the U.S. Open, third by one shot in the British Open and tied for sixth at the PGA Championship, two shots from making the playoff.

Mickelson's teammates, publicly at least, do not seem to be questioning his decision.

"I would say that personally, I don't like to change," said veteran Jay Haas, at 50 the oldest player in the competition. "I guess I won't say I'm afraid to change, but the unknown factor just doesn't make me comfortable. I played with Phil on Tuesday, though, and he didn't seem to be struggling with that change. I don't think he would change, just to be changing. I think he would change to think that it's going to be better for him personally. I don't think there's been any talk in the locker room among other players or anything like that. It doesn't seem to be a big issue. He played awfully well."

Phil Mickelson caused a stir by switching from Titleist to Callaway clubs and balls two weeks before the Ryder Cup, but Mickelson insists it won't affect his game.