Glover's PGA Tour start in doubt because of knee injury Thu Jan 5, 2012 3:18pm EST (Reuters) - Lucas Glover's preparations for this week's Tournament of Champions at Kapalua in Hawaii suffered a major setback when he withdrew from the pro-am competition on Thursday because of a knee injury. The former U.S. Open winner sprained a ligament in his right knee while paddleboarding over the weekend and gave himself a "50-50" chance of teeing off in Friday's opening round, the PGA Tour website (www.pgatour.com) reported. American Glover, who triumphed in the 2009 U.S. Open at Bethpage, said his foot caught on the paddleboard as he fell, with his body tumbling in a different direction. Subsequent tests revealed the ligament sprain. Should Glover pull out of the PGA Tour's season-opening event, it would mark the second successive year a player has had to withdraw from the elite winners-only field due to an accident in the ocean. Twelve months ago, defending champion Geoff Ogilvy of Australia exited the tournament before the opening round after cutting his finger on coral while coming out of the water on the Hawaiian island of Maui.