"Wide receiver Michael Crabtree saw sporadic action for the 49ers before his troublesome left foot flared up in the second half of Sunday's 33-17 season-opening win over Seattle.

Crabtree said a postgame X-ray was negative, meaning he has not broken that foot a third time since 2009. A June 6 fracture shelved him throughout training camp and the exhibition season.

"I wasn't 100 percent. I was just happy to be out there for a little bit," said Crabtree, the 49ers' first-round draft pick in 2009. "Coach did a good job letting me know (to exit). He'd seen my limping a little bit. I was trying to hide it, trying to stay on the field."

Crabtree had one reception for 4 yards, and he dropped the only other pass that came his way, a 1-yard toss from Alex Smith. Crabtree also delivered a big hit on safety Earl Thomas at the end of Vernon Davis' 27-yard, second-quarter reception.

"I'm not winded at all," Crabtree said of his conditioning. "It's just my foot, an injury."

Coach Jim Harbaugh said the 49ers did not plan to limit Crabtree to a specified number of snaps. As for why he pulled Crabtree, Harbaugh said: "I felt that he wasn't 100 percent at that time, like he was when he started the game. ... Just watching him move, I didn't feel like he was up to 100 percent right there at that point in the ballgame.""