Johnson, who rushed for just 36 yards, rumbled 78 yards with a screen pass to set up Lawrence Tynes' 19-yard field goal with 1:36 remaining. The Chiefs rallied from 10 down in the fourth quarter to beat the Arizona Cardinals 23-20 on Sunday.
Leinart, in his first NFL start, completed his first six passes, two for touchdowns, against a Kansas City defense that had not allowed a scoring pass in 12 quarters to start the season.
Matt Leinart threw two first-quarter touchdown passes in the Cardinals' 23-20 loss to the Chiefs. The only other quarterback in the Super Bowl era to throw two or more first-quarter TDs in his first NFL start was Doug Pederson of the Eagles (Sept. 12, 1999 vs. Cardinals).
• For more Elias Says, click here
On his second pass play, Leinart called an audible from the line of scrimmage, then lofted a 49-yard touchdown pass to Anquan Boldin.
And with the clock winding down, Leinart drove the Cardinals into field-goal range. But Neil Rackers missed a 51-yard kick that would have tied it with 2 seconds to play.
"It was fun," Leinart said. "I had a good time out there, just playing football. ... I think we can take it as a positive. I think we moved up a little bit as an offense. That was my first start. Now we can just go from there."
Johnson's big play had an ugly ending when Arizona's Antrel Rolle grabbed the star running back's facemask and twisted his head as he fell out of bounds. Johnson lay motionless for a moment before getting up and leaving on his own.
"All I remember is trying to get back on my feet and try to move around and see if everything was working," Johnson said. "I wanted to be safe about it and see if there was really something wrong or not."
The personal foul penalty moved the ball to the Cardinals 4, but the Chiefs (2-2) couldn't punch it in and settled for the go-ahead field goal.
Johnson planned to have an MRI on Monday.
Arizona (1-4) moved from its 10 to the Chiefs 33 on its final drive, the last 26 yards on a pass to Troy Walters. But Rackers, who had connected from 41 and 45 yards earlier, was wide left.
Johnson 36 yards were his lowest rushing total in 16 games. He also dropped a pass, missed a handoff for one fumble that was charged to quarterback Damon Huard, then fumbled the ball away again later.
"I think it was the worst production game I ever had," Johnson said.
Until that final screen pass.
"I'm a firm believer when a guy gets into a funk, you make sure he gets the ball," Chiefs coach Herm Edwards said. "Great players, you've got to give them the ball back because they're going to find a way to make a play, and he did. He made a big-time play."
Leinart, inserted in place of mistake-prone Kurt Warner, completed 22 of 35 passes for 253 yards and two touchdowns. He was intercepted once. He also saw a pass dropped in the end zone by Bryant Johnson.
"He showed good poise and I think he had a good day," Arizona coach Dennis Green said. "He did a lot of great things."
Larry Fitzgerald caught a 5-yard touchdown pass from Leinart, then left the game late in the first quarter with a hamstring injury that Green said "looked fairly serious."
Fitzgerald said he would get an MRI on Monday.
"I've never had a hamstring injury or really an injury, period," he said.
Huard, starting for the third successive game in place of injured Trent Green, was 26-of-38 for 288 yards and two scores with no interceptions.
On the Chiefs' first possession, Huard and Johnson botched the handoff and Arizona's Chike Okeafor recovered at the Kansas City 41. Leinart went 4-for-4 for 37 yards, capped by a 5-yard toss to a wide-open Fitzgerald for a 14-0 edge.
The second quarter was a rough one for the rookie.
Leinart was sacked on consecutive plays by Jared Allen and Ron Edwards, then Bernard Pollard blocked Scott Player's punt out of bounds at the Arizona 6. Huard tossed a short pass to Johnson, who broke Karlos Dansby's tackle and scored to cut the lead to 14-10.
After Johnson's fumble was recovered by the Cardinals' Eric Green at the Chiefs 32, Rackers' 41-yard field goal put Arizona up 17-10 at the half.
Down 20-10 after three quarters, the Chiefs went 66 yards in seven plays, Huard throwing 15 yards to Samie Parker to cut it to 20-17 with 9:35 to play. Leinart's lone big mistake followed. Ty Law picked off the rookie's pass and Tynes' 40-yard field goal tied it.
The Cardinals have lost four in a row and play a Monday night game at home against unbeaten Chicago next contest. ... Johnson's rushing total was his lowest since he gained 34 yards in just seven carries against Philadelphia on Oct. 2, 2006. ...
Edgerrin James, who gained 71 yards on 24 carries, said the Cardinals are "making a lot of progress, but we still do stupid things. We're doing some of the stupidest things you can imagine."
- Terry McAulay