Kansas CITY, Mo. (AP) -- The Kanas City Chiefs put the game in the hands of their defense.
It came through one more time.
Alex Smith threw for 225 yards and two touchdowns, and the Chiefs held off the Cleveland Browns late in the fourth quarter to preserve a 23-17 victory Sunday and remain the NFL's lone undefeated team.
The Chiefs (8-0), off to their best start since winning their first nine games in 2003, built a 20-7 lead late in the first half before the Browns made it a game.
Jason Campbell, starting in place of the ineffective Brandon Weeden, threw for 293 yards and two touchdowns. His second scoring pass, a 17-yarder to Fozzy Whittaker out of the backfield, got Cleveland (3-5) within a field goal early in the third quarter.
The Chiefs kept stopping the Browns down the stretch, though. They were forced to punt with 3:55 left but managed to force Campbell out of the pocket on fourth down, and his pass back across the field bounced off Davone Bess's hands for an incompletion.
It was one of several drops for Bess, who also fumbled on a punt return.
Ryan Succop tacked on his third field goal of the game with 17 seconds left, and the Browns were unable to do anything with their final possession before time expired.
Jamaal Charles had 74 yards rushing for the Chiefs, who have leaned continuously on their defense this season. They cranked up the pressure on Campbell when it mattered down the stretch, and still have not allowed more than 17 points in a game this season.
Josh Gordon had five catches for 132 yards and a touchdown in what could be his final game for Cleveland. The Browns have been fielding offers for him ahead of the trade deadline.
The Chiefs never punted in the first half, a good indication of the way things were going.
They marched downfield on the game's opening possession before settling for Succop's first field goal, and then did the exact same thing when they got the ball back moments later.
Kansas City reached the end zone early in the second quarter when Smith found fullback Anthony Sherman out of the backfield on third-and-10. He picked up a couple of marvelous blocks and rumbled his way 12 yards for his first career touchdown and a 13-0 lead.
Meanwhile, the Browns' offense struggled to get on track, going three-and-out on their first three series. Campbell overshot a couple of wide receivers, but the real problem was their lack of a running game -- they had three carries for minus-1 yard at halftime.
It took some trickery for Cleveland to score. Campbell handed off to Willis McGahee, who flipped it back to the quarterback. He hit Gordon in stride for a 39-yard reception.
The good vibes on their sideline were short-lived, though.
Charles ripped off two long runs, including one to convert another third down -- the Chiefs were 9 of 12 in the half -- to get into Cleveland territory. Smith finished the drive by hitting Dexter McCluster down the seam for a 28-yard scoring pass.
The Browns managed to get a field goal to get within 20-10 just before the break, and then carried the momentum into the second half, closing within a field goal on Whittaker's TD catch.
That was as close as the Chiefs defense would allow them to get.