Bernhard Langer carded a 4-under 66 on Saturday to move three strokes clear of the field after three rounds of the Senior British Open.
Langer, the 2010 champion, finished 54 holes at 9-under-par 201. He will go for his 19th Champions Tour win on Sunday.
David Frost posted a 2-under 68 to move into second pace at minus-6. Mark Wiebe, who shared the second-round lead with Langer, managed an even-par 70. He dipped into third place at 5-under 205 at Royal Birkdale Golf Club.
Sandy Lyle (69), Peter Fowler (70) and Gene Sauers (70) share fourth place at minus-3, while Peter Senior (69) is one stroke back at 2-under 208. Corey Pavin posted a 1-under 69 to end three rounds in red figures at minus-1.
Langer, who has two Champions Tour wins this season, got off to a steady start with a birdie on the third to go with four pars in his first five holes. He converted back-to-back birdie chances at six and seven to move three clear of Frost and Wiebe.
After six consecutive pars around the turn, Langer stumbled to a 3-putt bogey at the 14th. That trimmed his lead to one over Wiebe, who birdied the 13th.
Langer, whose group was on the clock for being out of place, bounced back with his third birdie in three days at the 15th. After Frost birdied 17 to get within one of the lead, Langer responded as he birdied the 17th for the third day in a row.
The German missed a 13-footer for birdie at the last.
"I've hit so many good shots the last few days where they feel good and come off right where I want them to go and they go the proper distance," Langer said. "It's just fun playing golf that way because it doesn't happen very often."
Langer won his only two majors on the senior circuit in 2010 when he claimed the Senior British and U.S. Senior Opens in back-to-back weeks. However, he led entering the final round of the U.S. Senior and Senior British Opens last year and failed to hold those leads.
"It's always special to win any tournament, but to win a major and to win it on a golf course like this, would mean a lot. There's a lot of golf left. We all know that," said Langer. "There's somebody inside me that expects me to win, but I know there's 18 holes left, and there's a lot of shots to be pulled off and a lot of putts to be made. So golf is not over till it's over, and we've got 18 holes to play."
Frost poured in three consecutive birdies from the seventh to jump within one of the lead at minus-7. He stumbled off the pace with bogeys 10 and 14th.
The South African moved back within one of the lead thanks to birdies at 15 and 17, but he failed to convert a 12-foot par putt at the last and dropped three strokes off of Langer's pace.
"I have to do something really special. I have to find something that I'm confident with, that I can go out tomorrow and just find a little key thought," Frost stated. "It would be special to win here at Birkdale. I've come here many years, so hopefully we can talk about that tomorrow night."
Wiebe had two bogeys and a birdie on the front nine along with a birdie and eight pars on the back.
NOTES: Langer has 19 top-10s in his previous 27 Champions Tour majors ... If he goes on to win, Langer would join Gary Player, Bob Charles, Brian Barnes, Tom Watson and Loren Roberts as the only six multiple winners of this event ... Langer is just 2-5 when leading at 54 holes at a Senior major ... Players in the last group have won four straight Champions Tour events, and nine of the last 14 overall ... Defending champion Fred Couples carded a 68 to jump into a share of 22nd at plus-4.