Woods, who was granted an extension to enter by the PGA of America for the year's final major, said he was "pain-free" after he played nine holes with fellow Americans Davis Love III, Webb Simpson and Steve Stricker.
Woods, who said his latest back injury was not related to his surgery in March, hit the driving range with swing coach Sean Foley before his practice round. His caddie, Joe LaCava, had been at Valhalla since Monday preparing for the event.
When last seen before Wednesday, Woods was gingerly walking off the course at Firestone Country Club after withdrawing from the Bridgestone Invitational because of spasms in his back. He had surgery in March to relieve a pinched nerve in his back.
“Basically, when I landed in the bunker, my sacrum went out,” said Woods, who had to hit an awkward shot from the rough above a fairway bunker at the second hole Sunday and jumped down into the bunker after losing his balance.
“It was a different pain than what I had been experiencing,” added Woods, who returned to his home in Florida on Sunday to receive treatment from a trainer. “So I knew it wasn't the site of the surgery. Once he put it back in, the spasms went away. And from there, I started getting some range of motion."
If Woods enters the PGA Championship -- he has until 5:35 a.m. Pacific time to join Phil Mickelson and Padraig Harrington on the first tee -- it will be his fourth tournament since his surgery. He hasn't fared well after the surgery, missing the cut at the Quicken Loans National and finishing 69th at the British Open in his first two tournaments.
Kerry Haigh, the PGA's chief championships officer, said alternates are on site to replace golfers who can't compete.
"Every PGA Championship, we always have the alternates literally on the putting green or practice range during the tee off, the two-hour tee period," Haigh said. "So if any player either misses their tee time because they were running late, caught in traffic or whatever, or somebody calls and says they are withdrawing, that alternate is there ready to go."
Tribune staff writer K.C. Johnson contributed to this report.