McIlroy made birdie at the 22nd hole, Harding Park’s first hole, and Casey, who spent most of the night battling a sickness, struggled to a par.
“Saw my lunch again last night,” Casey said. “When you’re giving up 10 yards to Rory anyway and you stand on that first tee not in the best form, suddenly I’m giving up 10 or 20 yards. But I am a big fan of beware of the injured golfer and I actually hit two very, very good golf shots.”
Casey said he may have had food poisoning and that the hardest part of the morning was standing over his chip shot behind the first green.
The Englishman put a heavy jacket on between shots and had about 260 yards to hole for his second shot, which sailed long and into a bad lie behind the green, but he was still encouraged by his play after two weeks off.
“I hit two cracking shots into No. 1,” he smiled. “I take a lot of positives, but I can’t wait to get to Florida.”