ARDMORE, PENNSYLVANIA (AFP) - Four-time Majors champion Phil Mickelson and second-time Major starter Billy Horschel remained tied for the lead after the second round of the US Open, as Saturday challengers faded.

But world No. 1 Tiger Woods lurked only four strokes off the pace. Woods seeks a record-tying fourth US Open crown.

The storm-hit Open, thrown off schedule after play was halted for more than four hours on Thursday, continued in perfect conditions on Saturday with 73 players making the cut at eight-over-par 148.

Mickelson, a five-time US Open runner-up still chasing the elusive trophy, and fellow American Horschel, set the overnight pace at one-under 139 for 36 holes.

England's Luke Donald and Justin Rose, seeking their first Major win, and American Steve Stricker, trying to become the oldest US Open champion at age 46, were also in the clubhouse just one stroke back on 140.

"I fought hard to stay in there and hit a lot of good quality shots," Mickelson said.

"I'm very excited about the opportunity this weekend,"

Horschel fired a 67, becoming the first player to reach all 18 greens in regulation in a US Open round since the statistic was first kept in 1992.