SAN FRANCISCO -- Phil Mickelson tweaked his back in the days following his Sept. 27 victory at the Tour Championship, and the injury is troublesome enough that he is limiting his practice at the Presidents Cup to just nine holes per day.
But Mickelson said the minor back injury that flared up last week during practice will not keep him out of the Presidents Cup matches this week at Harding Park.
"It's not a big deal. I'm fine," Mickelson said after holing a 60-foot birdie putt to finish off a friendly match during practice. "This is being way overblown."
Mickelson says he is limited practice "just to be cautious until the inflammation goes down," and that he was able to swing freely without any pain or discomfort.
U.S. captain Fred Couples said Tuesday that the limited practice rounds are a "precaution."
"It was a little bit of a concern until I saw him on the range today," Couples said. "Anybody's going to tell you they're doing good. You have got to watch them, though."
The Presidents Cup is a Ryder Cup-style tournament that pits a 12-man American team against 12 International players from outside of Europe. It begins Thursday and players are required to play all four days.
Mickelson won the finale to the FedEx Cup playoffs at East Lake in Atlanta by three strokes over Tiger Woods -- his third victory of the year -- and credited much of his good play to resurgent putting with the help of former PGA champion Dave Stockton.
Mickelson said his lower back tightened up Friday when he was practicing his chipping and putting.
He then contacted Couples to ask if Tom Boers, a noted physical therapist, would be at this week's Presidents Cup. That raised Couples' awareness, because he has had numerous back issues in his playing career and has often sought the help of Boers.
"I said, 'Why do you ask that?' He said, 'I'm just curious.' I laid into him, 'This is the biggest week of my life, you've got to tell me what's going on,' " Couples said, smiling.
"So Tom came to see him and got him going and [International captain] Greg [Norman] and I have both worked with Tom and he's a miracle worker. [Mickelson] looked good on the range."
If it were determined that Mickelson cannot play, Couples would be allowed to pick an American to take his place.
Once the competition begins, however, no substitutes would be added and Norman would pick a player from his squad to sit out.
All 12 players on each side compete on Thursday in foursomes (alternate shot) and four-ball (best ball) matches. The same format applies on Saturday, although just are just five matches in the morning and five in the afternoon, meaning two players from each squad sit out each session. There are 12 singles matches on Sunday.
"I don't see it as a problem," Couples said. "I have to get through Thursday with Phil before I get to Saturday. I know he's going to tell me if he wants to play both matches, but it just depends."
Bob Harig covers golf for ESPN.com. Information from The Associated Press was used in this report.