Masters Leaderboard 2012: Tracking the Day 2 Action

Lee Westwood held on to his lead through four holes in Friday's second-round action at Augusta, but it was a tenuous grasp, with a whole bunch of Americans nipping at his heels.

Westwood remained five-under with five pars on Thursday, but Ben Crane was steadily gaining on him with a 31 through eight holes. Crane, who ended the first round three-under par and two strokes back from Westwood's lead, birdied the second hole to pull within a stroke of Westwood.

Though Zach Johnson looked to be gaining on him through much of the front nine, a double-bogey on the ninth hole did him in. He started off rocky with a bogey on the first, but more than made up for it with two consecutive birdies and five pars. The last-hole mishap, however, put him one over with a 37 on the front nine.

Jason Dufner remained four-under through six, birdying three holes on the front nine to gain a stroke after shooting a 69 in the first round. A double-bogey on the fourth hole was a tough break for Dufner, but he didn't let it spiral and looks to be gaining steam.

Not gaining steam is Peter Hanson, who—after shooting an impressive four-under 68 on Thursday—began the second round with a double-bogey on the first hole. He made up for it slightly with a birdie on the second.

Jim Furyk and Bubba Watson both held strong at three under early in the second round. Furyk bogeyed the first hole but followed up with two birdies and two pars, and Watson started off the day with three straight pars.

Elsewhere on the leaderboard, Rory McIlroy parred the first two holes and birdied the third as he looks to improve on a one-under 71 after the first round.

Phil Mickelson, who finished the first round with a two-over 74, parred holes one and two in the second round on Friday.