DiMarco returned to the course after play was suspended Thursday following a 5 1/2 hour weather delay and tallied a birdie at the par-3 sixth for a round of 5-under-par 67. DiMarco also held the first-round lead at the Masters in his debut in 2001 and ultimately tied for 10th.
World No. 1 Vijay Singh shares second place at 4-under-par 68 with England's Luke Donald, who is making his first appearance at Augusta. Australians Mark Hensby and Stuart Appleby followed at 3-under-par 69.
Defending champion Phil Mickelson was left on the course as darkness set in on Thursday. He birdied the par-3 12th Friday morning, but gave a shot back with a bogey at the par-four 14th. Mickelson then parred his way in to join Ryan Palmer at 2-under-par 70.
DiMarco has come close in the past at the majors. He held the lead at Augusta in 2001 and shared the top spot with Mickelson heading into the final round last year. He lost in a playoff at last year's PGA Championship, but 2005 has given him another opportunity.
He started on the 10th on Thursday and bogeyed his first hole of the round. DiMarco responded with a birdie at the par-5 13th and collected a birdie at the par-5 15th to make the turn at 1 under.
DiMarco caught fire on the front side and drained a long birdie putt at the par-4 first. He then birdied the par-5 second and hit a wedge to 7 feet for a birdie at the par-4 third to claim the top spot at 4 under.
DiMarco then parred the fourth and was playing the par-4 fifth as darkness was quickly setting in. The horn sounded when DiMarco was in the fairway, but he had the option of finishing his hole. He played his second into a front bunker and knocked his third out to 8 feet.
The choice to finish his hole proved to be a good one and DiMarco rolled in the par-saving putt. He continued his fine play Friday morning and collected a birdie at the sixth to secure the opening-round lead.
Three-time Masters champion Tiger Woods had some bad breaks on Thursday, including a bogey at the par-5 13th after a lengthy eagle putt rolled off the green and into the water. Woods also bogeyed the par-4 first after his approach hit the flag. After play was called on Thursday, Woods nearly suffered a penalty at the 14th for standing in line with his putt when he tapped in for par. It was determined that Woods was not at fault, however.
Woods came back to Augusta National Friday morning and picked up a birdie at the fifth. He then bogeyed the sixth, but got that shot back with a birdie at the seventh. The roller coaster finish continued with a bogey at the eighth and Woods parred the ninth for a round of 2-over-par 74.
Ernie Els was one shot further back in a group at 3-over-par 75.
Reigning U.S. Amateur Ryan Moore is tied with Retief Goosen, Adam Scott, Thomas Bjorn, Chris Riley and Thomas Levet at 1-under-par 71.