ST ANDREWS (AFP) - Jordan Spieth got his bid for a third straight major title off to a strong start at the British Open on Thursday, birdieing his first two holes and getting to three under after five holes.

The 21-year-old Texan is aiming to become just the second man, after Ben Hogan in 1953, to win the Open Championship in the same year as the Masters and US Open.

Spieth sunk a six-footer at the wide-open first at St Andrews and went two under with an eight-foot putt at the second.

He could have been three-under after three holes at the next but watched a nine-footer slip past. But he was on in two at the fifth and secured his third birdie of the day.

Sweden's David Lingmerth was the early pace-setter, birdieing the first four holes and then reaching the turn in seven-under 29.

Dustin Johnson, who took second place behind Spieth at the US Open, and was playing alongside him on Thursday, was at four under after five holes.

Tiger Woods had a bad start and was two over after two holes, both due to poor approaches.