Williams was seen with Scott on Saturday at Congressional Country Club, site of the 111th U.S. Open, and speculation began about whether the arrangement could be more than temporary, given Woods' unclear status due to a knee and Achilles injury which is keeping the three-time U.S. Open champion out of the tournament that begins Thursday.
"Adam and Steve are friends and have been good friends for a while, and Adam asked Steve if he would help him out," said Mark Steinberg, Woods' agent. "Steve then called Tiger. Like any athlete or competitor, Steve doesn't want to miss a major, either."
Asked if this could be a long-term relationship Monday, Scott replied, "No. He is Tiger's guy and that's how it is."
Williams has been on Woods' bag for 13 of his 14 major championship victories. He began working with him at Bay Hill in 1999. Prior to Woods, Williams had a lengthy career as a caddie, including stints with Raymond Floyd and Greg Norman.
He had made the trip from his home in New Zealand last weekend to a home in Oregon, anticipating that he would be working for Woods at Congressional next week. Woods has played in every U.S. Open since turning pro and has not missed once since 2004, the year prior to first becoming exempt for the tournament.
Scott, 30, a seven-time winner on the PGA Tour, finished tied for second, two strokes behind Charl Schwartzel at the Masters, where Woods tied for fourth. A few weeks later he parted ways with his long-time caddie, Tony Navarro, who had worked for him for several years after a long stint with Norman and is now working for Angel Cabrera.
The Australian tried to keep this all in perspective, especially when asked how much he relies on a caddie, such as reading putts.
"Look, I generally try to go play my game," Scott said Monday. "But if they pay attention the whole day and if I do have a question, they know what to do. That's what a good caddie is all about. There's a reason why I'm here. It's because I know how to play. If I don't trust myself or my instincts, a good caddie knows when to step in and say the right thing."
Veteran caddie Mick Noran worked the Crown Plaza Invitational for Scott, who has yet to decide on a permanent replacement.
"He's just helping him out this week," Steinberg said. "Adam is between caddies right now."
Woods' last tournament was the Masters. He played only nine holes at The Players Championship before withdrawing due to the injuries he said would also keep him out of the U.S. Open. Woods said he hopes to return to the AT&T National, which begins on June 30.
Williams also will be at the AT&T National in two weeks outside Philadelphia, working either for Scott or Woods if his regular boss can return to golf by then. But if it was strange to see Williams tending to Scott, it was slightly odd for the Kiwi caddie, too.
"I haven't caddied for another player since I started with Tiger," Williams said Monday.
Bob Harig covers golf for ESPN.com. He can be reached at BobHarig@gmail.com. Information from the Associated Press contributed to this report.