Golf-Big finish lifts Streb to PGA Championship lead

* Walker, Streb lead by two * Day and Argentina's Grillo two back * Stenson lurks three off the pace (Updates at end of round) By Larry Fine SPRINGFIELD, New Jersey, July 29 (Reuters) - Americans Jimmy Walker and Robert Streb shared a two-shot, 36-hole lead at the PGA Championship on Friday with heavyweights Jason Day, Henrik Stenson and Martin Kaymer lurking nearby. Streb, who has one PGA Tour win to his credit, rolled in a 21-foot birdie putt on his last hole, the ninth at Baltusrol, for the 30th round of 63 ever shot in a major championship to tie Walker (66) with a nine-under-par total of 131. World number one and defending champion Jason Day was tied with 23-year-old Emiliano Grillo of Argentina on 133, one stroke ahead of British Open winner Henrik Stenson. Day came alive after a double-bogey at the par-four seventh put him two-over for the round. The Australian roared back with seven birdies in his next eight holes on his way to a 65, while Grillo birdied four holes on his first nine in shooting 67. Stenson, who fired a sensational final-round 63 to outduel Phil Mickelson at Royal Troon two weeks ago and set a British Open scoring record with a 20-under total, posted his second successive 67 for fifth place on 134. Another shot back were 2010 PGA winner Martin Kaymer (69), and Americans Patrick Reed (65) and Brooks Koepka (67). The second round began ominously when pouring rain led to a 41-minute suspension of play a little more than an hour after the first tee shots of the day. That downpour followed an inch (2.54 cm) of rain overnight that drenched the layout and made the tricky Baltusrol greens more receptive for approach shots. But the sun broke through and the course dried as the day wore on, setting up a flurry of good scores that set the stage for a tension-filled battle over the last 36 holes of the year's final major championship. (Reporting by Larry Fine; Editing by Mark Lamport-Stokes)