The 36-year-old managed nine practice holes on Tuesday along with a spell on the driving range but today's practice was aborted after a tee shot followed by a seven-iron approach at Royal Birkdale.
He admitted that if it was any other tournament then he would have announced his withdrawal by now but he was going to give himself until the last possible minute to prove his fitness.
"If it wasn't the Open I would have pulled out," said Harrington. "I would have had treatment and then decided I couldn't risk it. But because it's Open week I'll make the effort."
Meanwhile, John Daly, another player who has previously tasted Open success, is also struggling with injury.
The powerful American is ignoring medical advice to play at Royal Birkdale, saying: "It's just been very tough to play at all this year because of the injuries and the same last year.
"My doctor told me I shouldn't play. I've got tendonitis in my left elbow and I had a cyst on my right hand that was a calcium buildup that we thought was arthritis, and they got that out. So it's just been one thing after another.
"It's pretty much the first time I haven't listened to my doctor in two years."



