"It's not good, of course, when a guy goes down in open grass and is not touched by anyone," Tomlin said. "Experience tells me that, in general, that's not good."
Mendenhall went down after a 5-yard gain and immediately grabbed his right knee. He walked slowly to the sideline, slapping hands with some teammates on his way to the bench and didn't return.
After the game, Mendenhall left the stadium on crutches, his head hanging in disappointment. Tomlin said Mendenhall would be examined when the team gets home.
"You should anticipate that he won't be participating next week," Tomlin said.
Mendenhall rushed for 38 yards on eight carries before getting hurt, giving him 928 yards this season.
"Obviously, I didn't want him to go back in the game," Kubiak said. "We'll know better where we're at (Monday) at this point."
The 36-year-old Delhomme, signed Nov. 29 in the wake of season-ending injuries to starter Matt Schaub and backup Matt Leinart, completed 18 of 28 passes, including a 5-yard touchdown pass to Bryant Johnson with 14 seconds left. Kubiak called for a 2-point conversion at the end. But after a false start penalty, backup center Thomas Austin snapped the ball over Delhomme's head and the game was over.
Denver lost two offensive starters in the first half of its 7-3 loss to Kansas City when right guard Chris Kuper broke his left leg and fullback Spencer Larsen hurt a knee.
Kuper's replacement, Russ Hochstein, left in the fourth quarter with an undisclosed injury and Chris Clark replaced him.
"Pre-game he scared us all. He fell out and he had a little fainting issue in the locker room," wide receiver Larry Fitzgerald said. "We were all nervous about him being ab le to play today and he fought through that and was able to go out there and perform and get our team a win. That shows the kind of toughness he has."