The San Francisco 49ers' Pro Bowl tight end, George Kittle, left Thursday night's game against the Arizona Cardinals in the first quarter with what looked like it could be a significant injury. He took a hit from an opposing player's helmet in the knee area and went down in pain.

Kittle's MRI revealed that his "knee is good," according to Ian Rapoport of NFL Network. The thought is that the tight end should not miss significant time, but a specific timetable for his return has not yet been revealed. However, given his comments after the game, it sounded like Kittle expected to play in the 49ers' November 11 matchup against the Seattle Seahawks.

Kwon Alexander also left Thursday night's game with a chest injury. His MRI revealed a torn pectoral, which will land him on season-ending injured reserve.

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"I know it was scary, but the fact that they felt good enough with him coming back in the game, just talking to everyone last night, I'm feeling pretty optimistic about Kittle," head coach Kyle Shanahan said Friday morning via a conference call before learning the results of the MRI. "I know he played through a lot of stuff. It's going to be tough on him this week, but I feel pretty good that it's not going to be a longer-term thing, and hopefully, we'll be able to get him back this week."

During the game, Kittle was examined, started jogging on the sideline, and then returned to the action on the offense's next drive. He wasn't able to finish the game, though, and was out of the lineup and observing from the sideline in the fourth quarter. Kittle finished the game with six catches for 79 yards and a touchdown.

"I know if something happens, I try to push through it as much as you can," Kittle told reporters after the game. "But if it comes to the point where I feel like I'm a liability to the team, and I'm not the best man for the job, then I definitely have to talk to my coach about it, and we make a decision about it.

"I definitely thought that Dwelley was definitely more mobile than I was in that fourth quarter."

Kittle's touchdown reception occurred after the injury. Even fellow tight end Travis Kelce of the Kansas City Chiefs was impressed.

The 49ers ended up winning the game 28-25 and improving to 8-0 for the first time since 1990 and just the second time in franchise history.

Kittle was asked about the injury after the game.

"It is what it is," Kittle responded. "Football, stuff happens. You either decide to go back out or you don't, and I tried to give my team everything that I could. Then, fourth quarter, couldn't really go anymore, and happy to have a guy like Ross Dwelley and Levine Toilolo in there stepping up."