Darren Clarke has withdrawn from the Shell Houston Open to return home to be with his wife, who is battling cancer.

The Ulsterman pulled out of the event after firing a four-under-par 68 in the first round, which left him just two shots off the lead.

Clarke's manager Andrew Chandler said the player, who pulled out of several events because of his wife Heather's illness last year, took the decision to head home from the latest event following test results.

The Dungannon player managed six birdies with a pair of bogeys to trail first round clubhouse leader Stuart Appleby by two shots.

One stroke behind Clarke was Englishman Greg Owen in a tie for ninth alongside defending champion Vijay Singh.

Padraig Harrington is two-under through the front nine.