Edmond, Okla. • Colin Montgomerie thought it would be tough to keep his advantage from the first round at the U.S. Senior Open, and it was.
The Scotsman shot an even-par 71 on Friday and leads Scott Dunlap by one stroke after the second day of the tournament.
Montgomerie opened with a 65 on Thursday, and then held off the field in mid-90s heat and high humidity. He is at 6 under after two rounds.
"It's not easy to repeat a good round as yesterday's was, but this was as good, to be honest," he said. "Seventy-one out there was a good effort. Breezy conditions, windier than it was yesterday, warmer and with the pack coming at you it's never easy."
Dunlap had a 69 in the first round and a 68 in the second to get to 5 under. He was at 2 under after starting on the back nine, and then went back to the front nine and birdied Nos. 2, 5 and 7 on his way to a 32.
"I have been particularly good with the putter this week," Dunlap said. "Been tidy. I have made a couple, made all my short ones. You know, those will be big in any tournament, for sure, but especially a major."
Dunlap has one bogey in 36 holes on a course regarded as one of the most difficult in the United States.
"Take my hat off to that," said Bernhard Langer, who is tied for third. "That's good playing. It's all I can say. It's very difficult not to make bogies here. You can bogey every single hole. There's no easy hole out here, and that's very good ball striking or incredible scrambling, whatever he does."
PGA Tour
In Silvis, Ill., Zach Johnson and William McGirt were at 12-under-par 130 and tied for the lead at the halfway point of the John Deere Classic. They were a stroke ahead of Steven Bowditch, Johnson Wagner and Brian Harman.
Three-time Deere winner Steve Stricker shot a 65 Friday for a 133 total to vault into contention at the par-71 TPC Deere Run, and was tied for sixth with Rory Sabbatini, Ryan Moore and Todd Hamilton.
Johnson, the Deere winner in 2012, shot a 4-under 67 in the afternoon despite two bogeys in his last four holes. That dropped him into a tie with McGirt.
McGirt, 35, is looking for his first PGA Tour victory.
Women's British Open
In Southport, England, American Mo Martin carded her second straight 3-under 69 in the Women's British Open, taking a three-shot lead over Beatriz Recari of Spain and former U.S. Women's Open champion So Yeon Ryu going into the weekend. Michelle Wie, coming off her first major in the U.S. Women's Open at Pinehurst No. 2, followed her highest score of the year (75) with one that was even worse, a 78, to miss the cut by three shots.
Friday's scores
U.S. Senior Open
At Oak Tree National Golf Club
Edmond, Okla.
Purse • TBA ($2.6 million in 2013)
Yardage • 7,219; Par • 71
Second-round leaders
Colin Montgomerie 65-71 136
Scott Dunlap 69-68 137
Gene Sauers 69-69 138
Bernhard Langer 69-69 138
Lance Ten Broeck 70-69 139
Mark Brooks 68-71 139
Jeff Sluman 70-69 139
Doug Garwood 70-69 139
Vijay Singh 69-71 140
Wes Short Jr. 73-68 141
Tom Lehman 72-69 141
Kirk Triplett 69-72 141
David Frost 71-71 142
Marco Dawson 66-76 142
Olin Browne 70-72 142
Woody Austin 72-70 142
Tom Kite 73-70 143
Esteban Toledo 73-70 143
Sonny Skinner 73-70 143
Joey Sindelar 72-71 143
Barry Lane 74-69 143
Robin Byrd 77-67 144
Joe Durant 71-73 144
Russ Cochran 70-74 144
Rocco Mediate 70-74 144
Bart Bryant 71-73 144
Steve Pate 72-72 144
Chris Williams 72-72 144
Kevin Sutherland 73-72 145
Loren Roberts 73-72 145
Brad Bryant 73-72 145
Corey Pavin 72-73 145
Philip Golding 72-74 146
Scott Hoch 75-71 146
Michael Allen 73-73 146
Bill Glasson 73-73 146
Tom Byrum 71-75 146
Peter Senior 73-73 146
a-Jeff Wilson 70-76 146 Also (failed to make cut) Dan Forsman 76-74 150
PGA-John Deere Classic
At TPC Deere Run
Silvis, Ill.
Purse • $4.7 million
Yardage • 7,268; Par • 71 (35-36)
(a-amateur)
Second-round leaders
William McGirt 64-66 130
Zach Johnson 63-67 130
Steven Bowditch 64-67 131
Johnson Wagner 66-65 131
Brian Harman 63-68 131
Steve Stricker 68-65 133
Todd Hamilton 64-69 133
Ryan Moore 66-67 133
Rory Sabbatini 63-70 133
Jerry Kelly 66-68 134
Robert Streb 65-69 134
Charles Howell III 66-68 134
Kevin Na 68-66 134
Kevin Tway 65-69 134
Bud Cauley 67-67 134 Also
Daniel Summerhays 69-68 137 Women's British Open
At Royal Birkdale Golf Club
Southport, England
Purse • $3 million
Yardage • 6,458; Par • 72
Second-round leaders
a-amateur
Mo Martin 69-69 138
Beatriz Recari 74-67 141
So Yeon Ryu 71-70 141
Sun-Ju Ahn 75-67 142
Julieta Granada 72-70 142
Ariya Jutanugarn 75-68 143
Gwladys Nocera 73-70 143
Amelia Lewis 72-71 143
Amy Yang 71-72 143
Eun-Hee Ji 74-70 144