Allen's 63 at US Senior Open gives him 5-shot lead, biggest ever at tournament's midway point

Michael Allen shot a 7-under 63 Friday and broke away from the pack for a 5-stroke lead after the second round of the U.S. Senior Open.

Allen was among seven players who shared the first-round lead at 3-under. He birdied five of the first eight holes and eagled the par-5 14th while shooting his best round of the year in hot, breezy conditions at the par-70 Omaha Country Club.

Allen's 36-hole lead is the largest in the event's 34-year history.

Rocco Mediate, at 5-under, is his closest pursuer. Mediate finished with 14 straight pars while shooting a bogey-free 67. Jeff Sluman, who also shot 67, is at 4-under after missing an 8-foot par putt on the 18th.

Allen was short on his birdie putt on the last hole, ending his bid to match the U.S. Senior Open record of 62 by Loren Roberts at Prairie Dunes in 2006.