Immelman fired his second straight 4-under 68 at the Augusta National Golf Club and his 136 total put him one shot in front of Brandt Snedeker. Mickelson shared third place at 139 with Steve Flesch and Ian Poulter. Stephen Ames and Paul Casey were at 140.
Woods, seeking his fifth Masters title, was one of seven players tied for 13th place at 143. Woods recorded four birdies in a round of 71, but bogeyed the par-5 second, the easiest hole on the course.
The world's top-ranked player hit his second shot at the 18th hole onto the 10th tee and managed to make an amazing par. He will need a near-record comeback during the weekend to win the tournament.
Jack Burke Jr. set the Masters record for largest 36-hole comeback by rallying from eight shots behind to capture the 1956 tournament.
"Obviously I've got to make a few more birdies and eliminate the mistakes," Woods said. "But on this golf course anything can happen."
Cooler, windier and possibly rainy weather was forecast for the weekend.