(CNN) -- England's Lee Westwood stayed calm in the face of a burst of sustained brilliance from Phil Mickelson to lead the American by a shot going into the final round of the U.S. Masters with Tiger Woods four adrift.
Mickelson sent the Augusta National galleries wild with successive eagles followed by a birdie to wrest the lead from the Ryder Cup star on the back nine, but he bogeyed the 17th to give up his advantage.
Westwood, who shared the overnight lead with compatriot Ian Poulter, opened up a big lead around the turn before the 39-year-old Mickelson gave a reminder of his incredible talents.
He first drained a seven-footer to grab his second eagle of the tournament at the par-five 13th, then holed his 139-yard approach to the par-four 14th.
He was close to repeating the dose with his approach to the 15th but had to settle for a mere birdie.
Westwood, who had seemed in total control in pursuit of his first major, dropped his first shot of the day but recovered with a further birdie on the 15th on the way to a four-under 68.
It left him in the lead on 12-under 204, with Mickelson breathing down his neck after a 67.
For once, Woods was left in the shadows as he struggled with his game and his temper on the way to a two-under 70, making a birdie three on the last to improve his chances for a last-day charge.
He is tied for third with his playing partner of all three days KJ Choi of Korea on eight-under 208 in pursuit of his 15th major and fifth green jacket at Augusta.
Veteran crowd favorite Fred Couples also got in the act with a birdie-eagle burst at 14 and 15 and he is in fifth at seven-under after a 68.
Mickelson is scenting victory on the final day after his back nine heroics.
"I haven't played this well in a long time and I am looking forward to it. Today has been a good day and I am excited about Sunday," he told gathered reporters.
European number one Westwood claimed he had not been affected by the huge roars that greeted Mickelson's memorable charge.
"I felt very calm out there and confident in what I was doing. Every aspect of my game felt good," he said.
By contrast, Woods, returning to golf after a sordid sex scandal, looked ill at ease with himself and showed his frustrations with several outbursts.
But he showed his fighting qualities to stay in contention and he is still hopeful after "tough day."
Woods added: "As it is I am only four back so a good round tomorrow and you never know. The birdie at the last was nice."
A trio at six-under, American pair Hunter Mahan (68) and Ricky Barnes (72) and Poulter, who struggled to a 74, may also harbor hopes of victory, but history points to one of Westwood or Mickelson donning the green jacket.