The Latest: Jordan Spieth is the golfer to beat as British Open begins at St. Andrews

Marshals stand in the rough on the sixth hole during a practice round at the British Open Golf Championship at the Old Course, St. Andrews, Scotland, Wednesday, July 15, 2015. (AP Photo/Alastair Grant) (The Associated Press)

United States’ Jordan Spieth drives a ball from the 12th tee during a practice round at the British Open Golf Championship at the Old Course, St. Andrews, Scotland, Wednesday, July 15, 2015. (AP Photo/David J. Phillip) (The Associated Press)

The Latest from the 144th British Open, being held on the Old Course at St. Andrews (all times local):

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7 a.m.

With all eyes on Jordan Spieth's quest for the Grand Slam, the British Open is underway on a cool, partly cloudy morning at the Old Course.

Englishman Greg Owen, playing in the first group, rolled in the first birdie of the tournament at No. 1 early Thursday. He was joined by Australian Rod Pampling and Irish amateur Paul Dunne, who both started with pars.

The bigger names will tee off later. Spieth, who already won the Masters and the U.S. Open, is scheduled to tee off at 9:33 a.m. in a group with fellow American Dustin Johnson and Japan's Hideki Matsuyama.

Spieth won the second leg of the Grand Slam last month at Chambers Bay, taking the title when Johnson three-putted for 12 feet at the 72nd hole. No player had won the modern version of the Slam, which also includes the PGA Championship.

Spieth doesn't have to worry about his chief rival. Defending champion Rory McIlroy is sitting out the British Open after injuring his ankle playing soccer with friends. Tiger Woods is another player who would've been considered a top contender, having won twice at St. Andrews. But he's mired in a terrible slump and has slipped to No. 241 in the world rankings.