South African Trevor Immelman was the early pace-setter on day two of the Houston Open, shooting six birdies on the way to a five-under-par 67 to move to eight under par and a one-shot lead over Swede Mathias Gronberg.

First-round leader Stuart Appleby was a late starter on the day, and after three holes had failed to improve on his six-under par overnight score.

Ireland's Padraig Harrington was in danger of missing the cut, his second-round 73 added to his opening 71 leaving him at level par, one outside the projected one-under-par cut-off point.

The Dubliner stood at one under par for his round at the par-four 18th, but carded a double-bogey six. Graeme McDowell of Northern Ireland was another late starter, and after three holes was also level par.

A double bogey on the fifth hole undermined Ian Poulter's charge up the leaderboard yesterday. Three birdies on the back nine saw Poulter start brightly after the previous day's 72 and he picked up shots at the third and fourth, before getting into trouble on the next hole en route to a 69 which left him in a tie for 19th.

Big-hitting John Daly enjoyed wildly contrasting fortunes on his front and back nines yesterday as he ended with a 72 after going out in five under par.

Daly dropped five shots in three holes, going double bogey, bogey and double bogey on the 11th, 12th and 13th, respectively, There was a brief respite when he birdied the par-five 15th before immediately surrendering another shot to the course at the next hole, a par three.