McNulty has four top 10s this year and is a perfect 16 for 16 in cuts made.
SNOQUALMIE, Wash. (AP) -- Mark McNulty went to the range after the first round of the Boeing Classic to try to figure out how a sizzling first nine holes got away from him.
McNulty didn't make the same mistake in Saturday's second round. McNulty shot a 7-under 65 and shares the lead heading to Sunday's final round.
Loren Roberts had four birdies in his final six holes to match McNulty's 65 and finish at 11 under. The duo holds a two-shot lead over Bernhard Langer and first-round leader Mark O'Meara.
McNulty was 4 under on his first nine holes Saturday, then made another four birdies on the back nine. He birdied Nos. 14 and 15, then curled in a long birdie putt on the 16th to share the lowest round of the tournament.
A few minutes later, Roberts matched McNulty's number with his birdie on 18.
McNulty has four top-10 finishes this year, including a victory at the Principal Charity Classic and a runner-up finish at the Senior British Open.
Thanks to his touch around the green, Roberts scrambled to a bogey-free round of 66. The steady putter made three consecutive birdies on 7, 8 and 9, then did the same thing on the back nine with consecutive birdies at 14, 15 and 16 before his birdie at 18.
Roberts won the Senior British Open last month, beating McNulty in a playoff.
Langer had a 6-under 66. He saved par on the 12th with a 15-foot putt, then got up and down from a greenside pot bunker on the 14th.
He narrowly avoiding hitting the ball into the hazard on the par-5 15th, as his second shot caught a tree limb and fell in a bunker instead. Langer ended up making bogey on 15, but rebounded with birdies on Nos. 16 and 17.
O'Meara led by two shots after the first round, but missed a number of short birdie putts throughout his second round. O'Meara suddenly found his putting stroke in the closing holes with birdies at 14, 15 and 16. He stumbled with a bogey at 17 when his tee shot on the par-3 hole missed the green, but rallied with a birdie at 18.
Craig Stadler came back from a jumbled pack to surge into contention. Dusting off a putter that was sitting in his closet for about five years, Stadler made six birdies for the second straight day. The difference Saturday was that Stadler didn't throw in the two double bogeys that ruined his first round.
Stadler heads to Sunday three shots back.