Darren Clarke withdrew from the Houston Open after shooting an opening round 68 in order to return home to be with his wife Heather who is battling cancer.

Clarke pulled out of the event after firing four birdies and two bogies which had left him two shots behind early clubhouse leader Stuart Appleby.

His manager Andrew Chandler said Clarke had taken the decision following his wife's latest test results. "Following ongoing tests, he has decided to return home," said Chandler.

Clarke pulled out of several events late last year because of his wife's illness.

Left to fly the flag for Ireland were Clarke's fellow Ulsterman Graeme McDowell and Padraig Harrington. McDowell had a steady start, finishing the day on level par 72.

Harrington was a later starter, and was one under par after 10 holes.

Americans Jerry Smith and DA Points were one shot off Appleby's lead.

A further shot back was Australian Aaron Baddeley, still riding high after his maiden tour win at the Heritage Classic in Hilton Head, South Carolina on Sunday.

Englishman Greg Owen was in a tie for eighth alongside defending champion Vijay Singh after they returned 69s.