Defending champion Jordan Spieth set an early clubhouse lead on day one of the US Masters golf.

The American signed off on a round of 66, leaving him 6-under par, although Ireland's Shane Lowry and World No 1 Jason Day were closing in fast as he finished.

The 22-year-old is looking for his third major title.

The World No 2 told Sky Sports News, getting round without dropping a shot was a big bonus.

"In order to stay bogey free, which isn't necessarily a goal, the goal is to try an shoot under-par each day. It's going to take a little bit more in the ball striking and the patience that we had today," he said.