The defending British Open champion is plagued by a sore right wrist, which forced him to cut back a practice round Tuesday and raised doubts about whether he will be able to tee it up this week.
Harrington insisted he'll be ready -- with one caveat.
"Obviously I have to manage it between now and then," he said after scaling back to chipping and putting over the final nine holes of his practice session. "I've got to make sure I don't do anything to it. If I do nothing to it between now and Thursday, I'll be able to play."
The Open can sorely afford to lose another top player. Woods, a three-time British champion and the world's No. 1 player, is sitting out the rest of the year to recover from knee surgery. Another leading American, Kenny Perry, decided to skip the tournament despite winning three of his past five events on the PGA Tour.
Despite taking a couple of days off, Harrington was clearly not at full strength during his first practice round of the week at Royal Birkdale. He played the front side but made sure to avoid hitting any shots out of the thick rough. At the turn, he was checked by a doctor and decided to just work around the green over the final nine holes.
Asked how his wrist felt, Harrington said, "Fuzzy. Tingly. I was weak in the wrist, and that's why I didn't play the back nine."
He sprained the wrist Saturday while swinging into an "impact bag," a sort of punching bag golfers use to strengthen that very crucial part of their bodies. He skipped two days of practice and got treatment, then decided to test it out on the course.
While Harrington failed to make it through all 18 holes, he is not considering dropping out.
"Not at the moment, no," he said. "Unless I injured it again. I can't see that happening. As long as I avoid doing that, I'll be OK."
Even if Harrington does play, he'll hardly be in top form. He intends to be back on the course today, but isn't sure if he'll be able to play more than nine holes. No matter what, he won't hit from the tall grass until it counts. Harrington said the next shot he hits from the rough will be in the tournament because he doesn't want to put any extra stress on his wrist.
The injury will surely make the job of defending the claret jug a little tougher. But nothing can take away from Harrington's memorable win a year ago at Carnoustie, where he hit two balls into the Barry Burn on the last hole of regulation but bounced back to beat Sergio Garcia in a four-hole playoff.