Immelman, who lost to Kim Furyk in a playoff last week at the Wachovia Championship, shot a 6-under 64. Scott, who had a four-stroke lead midway the third round, finished with a 69 to tie Immelman at 11-under 199 through 54 holes.
"It's a little disappointing not to keep it going because I played so good on the front nine," said Scott, who has three PGA Tour victories. "I'm still in the position of leading and I've just got to hang around for a bit longer tomorrow."
Immelman bogeyed the 72nd hole at the Wachovia last Sunday to drop into a playoff with Furyk.