U.S. Senior Open

Colin Montgomerie leads after the first round at the U.S. Senior Open.

Montgomerie shot a 6-under par 65 in oppressive heat Thursday at Oak Tree National in Edmond, Okla. The Scotsman started on 10 and birdied 14, 15 and 16 on the way to a 33 on the back nine. He birdied six, seven and eight to finish strong.

Marco Dawson is second after a 66. He also started on the back nine and shot 2 under, then was steady on the front nine before making birdies on seven, eight and nine.

PGA John Deere Classic

Zach Johnson, Rory Sabbatini and Brian Harman shot 8-under-par 63s to share the lead after the first round of the John Deere Classic in Silvis, Ill.

Johnson and Sabbatini played bogey-free golf, while Harman had nine birdies and one bogey on the par-71 TPC Deere Run.

They led 2004 British Open champion Todd Hamilton, Australian Steven Bowditch and William McGirt, the best afternoon finisher, by a stroke.

Johnson, who won the Deere in 2012 and lost it to Jordan Spieth in a playoff last year, birdied four of his first five holes and was 6 under on his opening nine.

Scottish Open

Rory McIlroy rolled in six birdies in seven holes around the turn to shoot a 7-under 64 and take a one-stroke lead after the first round of the Scottish Open in Aberdeen.

Refreshed after taking two weeks off, the No. 8-ranked McIlroy tamed windy conditions in northern Scotland to show his links game is in good shape ahead of next week's British Open at Hoylake.

Unheralded Swede Kristoffer Broberg shot a bogey-free 65 to sit just behind McIlroy on a leaderboard that includes Luke Donald (4-under 67). Defending champion Phil Mickelson shot 68.

Women's British Open

Ayako Uehara of Japan got her one mistake out of the way early and opened with a 4-under 68 to lead the Women's British Open in Southport, England.

Defending champion Stacy Lewis played in the same group as Uehara and shot 71 in what might be the easiest conditions all week at Royal Birkdale. U.S. Women's Open champion Michelle Wie struggled to keep the ball in play and shot 75.