Donald carded a second-round even-par 71 at Torrey Pines to be in a good position, just three strokes off the lead with the leaders yet to tee off at the US Open.

After a tough opening round, Harrington found his form and had the best round of the day yet when he signed for a four-under 67.

At two under through 10 holes, Donald was one stroke off the lead but a pair of bogeys later and he was three back with some work to do.

Donald had a pair of birdies on the front nine and started the back nine with a par at the 10th hole.

He then bogeyed the par-three 11th after missing the green and failing to get up and down. He dropped another shot at 12 after his approach found the deep rough to the left of the green.

He chipped out to about 15 feet but missed his par putt to drop to even par for the day but Donald rebounded with a birdie at 13 to get to one under and he stayed there until a bogey at the par-three 16th. He closed with a pair of pars and was at even par on 142 after 36 holes.

Harrington, the reigning Open champion, carded a 78 on Thursday and entered the second round knowing it would be a battle for him to make the cut.

He looked well on his way to bettering that score after playing his first nine in two under. He started his round on the 10th and made his first birdie at the par-five 13th before adding a birdie at the par-five 18th.

Harrington maintained his strong play coming home, birdying the second and seventh and just missing from 12 feet for birdie at the ninth. At three over, Harrington should easily make the cut and have a shot at making a move up the leaderboard if he can maintain his form.