ST. LOUIS -- Peter Jacobsen and his surgically repaired hip have passed two tests in the U.S. Senior Open. The biggest challenge is still to come.
Jacobsen followed up his 6-under 65 in the first round with a 70 on Saturday for a share of the lead with Craig Stadler.
Jose Canizares, who birdied the last three holes for his second straight 68, was one behind at 6 under.
Jay Haas, Tom Kite, Fuzzy Zoeller, Bob Gilder and D.A. Weibring were 5 under, and Champions Tour's top two money winners, Gil Morgan and Hale Irwin, were 4 under.
Not only are some of the 50-and-over tour's biggest names within striking distance, but Jacobsen is facing uncharted territory in his recovery from arthroscopic hip surgery three months ago. Because rain washed out play Friday, the tournament will finish Sunday with a 36-hole walk around 7,117-yard Bellerive Country Club course.
And Jacobsen is doing it on a hip still so painful that walking even 18 holes was impossible until this week. After six weeks on crutches, he entered two tournaments and withdrew because he couldn't finish the round.
Finally, thanks to a new stretching regimen, Jacobsen made it through 18 holes Thursday and again Saturday. What if he's still ahead Sunday, but the pain becomes unbearable?
"I'm not even going to think about that," Jacobsen said. "But, yeah, that's a concern."
Eighteen players were within five shots of the lead and 23 were under par.
Stadler faced potential disaster on the par-3 sixth hole when his tee shot went into the water. Still, he managed a bogey. He then birdied Nos. 11, 13, 15 and narrowly missed makeable birdie putts at 17 and 18. He said the back nine made up for a frustrating front side, where he was 1 over.
"I guess frustrating is a good word for it," Stadler said.
Jacobsen just missed a hole-in-one on the par-3 third hole, his tee shot hitting about an inch from the hole before spinning a couple of feet past. But he missed the short birdie putt. He made up for it on 18, chipping in from about 40 feet.
Never before has the entire field of a Champions Tour event played 36 holes in one day. And unlike regular Champions Tour events, carts are not allowed in the tournament.
"It's going to be a long, difficult day for everybody," Kite said.