The 49ers and their fans breathed a huge sigh of relief on Thursday night.

After giving up a touchdown to the Cardinals on the opening drive, All-Pro tight end George Kittle left the game with an apparent left knee injury on the 49ers' first play from scrimmage, but returned on the 49ers' second drive.

Kittle appeared to take a helmet to his left knee and was in a lot of pain initially. He was able to walk off on his own power, but had a noticeable limp. After going into the blue medical tent, Kittle came out and was seen jogging on the sideline.

After the 49ers forced the Cardinals to punt on their second drive, Kittle re-entered the game with the offense.

Kittle's knee clearly is fine, as he broke multiple tackles on a 30-yard touchdown at the end of the first quarter. 

The undefeated 49ers cannot afford to lose Kittle, so it's a good sign that he was able to come back just a few minutes later and look as good as ever on that touchdown.