The 26-year-old Australian shot a par 70 for the second straight day and completed 54 holes at 2-over 212. Woods put on a terrific ball-striking exhibition, hitting his first 17 greens before making bogey at 18 for a 69 and 214 total.
Baddeley and Woods will be paired in the final group today.
"I'm right there with a shot at it," Woods said when he finished, about an hour ahead of Baddeley.
"Tiger is a great person to play with because he's very complimentary when you hit a good shot," Baddeley said. "He's a great competitor and loves competition. I'm very comfortable playing with Tiger in a major."
Four men loom 3 strokes off the lead. British compatriots Paul Casey and Justin Rose are tied at 215 with Canada's Stephen Ames and Bubba Watson. Watson, who was 1 shot out at the start of the day, fell back with a triple-bogey 7 at the ninth but managed a 74.
Casey, who shot the low round of the championship, a 66, on Friday, fired a 72 yesterday, while Rose and Ames had 73s.
Steve Stricker carded the best round of the day, a 68, to tie former Open champion Jim Furyk and 36-hole leader Angel Cabrera at 216. Furyk birdied the final two holes for a 70, while Cabrera dropped down the leader board with a 76.
Baddeley, who won the 1999 Australian Open as an 18-year-old amateur but didn't get his first PGA Tour win until his fourth season on the tour in 2006, said he couldn't keep his eyes off the scoreboard.
"I was definitely watching the whole day," he said. "I saw Tiger was 1 or 2 under early, but you've got to expect that. Tiger loves playing in majors and loves winning. So I was expecting Tiger to have a good day."
Baddeley posted five birdies in his round. A 10-foot putt for a 2 at the par-3 13th gave him a 3-stroke lead. But the margin dwindled after bogeys at 15 and 16.
Baddeley's tee shot at the short par-4 17th came to rest in heavy rough on a severe slope that separated the fairway from a bunker. Despite the bad lie and awkward stance, he punched a nice shot to the left fringe and two-putted for par.
Baddeley gave himself some breathing room at the 484-yard 18th, sinking a 14-foot birdie putt to leave the course 2 shots in front.
Woods hit greens with monotonous regularity but one-putted only once, for a birdie at the third hole. He two-putted the par-5 fourth for his other birdie. He missed his only green at 18 after driving into a fairway bunker.
"Obviously, [the score] could have been really low, but on these greens . . . I had [only] two to three putts that I possibly could have made," he said.
At the start of today's final round, 15 players are within 6 shots of Baddeley's lead, but only three of them - Woods, David Toms (217) and Vijay Singh (218) - have won majors.
"They're going to deal with emotions that they've probably never dealt with before," Woods said of those seeking their first major. "It helps to have experience. I've been there before, and I know what it takes."
Regarding his unfamiliar situation, Baddeley said, "Obviously, I'm going to deal with some emotions because I've never been in this position before. But I've worked my whole life to be in this position, so I'm going to embrace it. I'm going to enjoy it."
And Oakmont will be ready and waiting.
Contact staff writer Joe Juliano
at 215-854-4494 or email@example.com.