Alex Smith, Chiefs Beat Kirk Cousins, Redskins on Last-Second Harrison Butker FG

It took late dramatics and a game-winning 43-yard field goal from Harrison Butker, but the Kansas City Chiefs remained the only undefeated team in the NFL with a 29-20 Monday victory over Washington at Arrowhead Stadium.

Just for good measure, Kansas City linebacker Justin Houston recovered a fumble on Washington's desperation play after the field goal and returned it for a touchdown.  

The 4-0 Chiefs scored on all four of their second-half possessions after a slow start, thanks in large part to the one-two punch of quarterback Alex Smith and running back Kareem Hunt. Smith finished with 293 passing yards, 56 rushing yards and two touchdowns, while Hunt added 101 yards on the ground in the victory.

Washington failed to contain the Kansas City backfield and dropped to 2-2 in the process.

While Smith was responsible for the Chiefs' two offensive touchdowns—one of which came on a throw to tight end Travis Kelce (111 receiving yards)—ESPN Stats & Info and Elias Sports noted Hunt joined rare company with his performance:

Kansas City won by two scores, but the contest came down to the final seconds. Butker's field goal with under five minutes remaining came after Smith directed a 14-play drive that was a testament to his ability to take what the defense gives him, keep possessions alive with his legs and remain efficient. 

That kick gave the home team the lead, but Washington answered with a Dustin Hopkins field goal with 50 seconds left.

Washington quarterback Kirk Cousins used his legs to pick up two critical first downs on the drive and actually led his team with 38 rushing yards. He also finished with 215 passing yards and two touchdown throws (one to Terrelle Pryor and one Ryan Grant), but Josh Doctson dropped a potential third touchdown in the end zone before Hopkins' field goal that could have won it for the visitors.

The drop proved costly, as Smith set up the game-winning field goal with a 37-yard completion to Albert Wilson.

Despite the victory, things couldn't have started much worse for Kansas City.

Pryor opened the scoring with his 44-yard touchdown reception, the Chiefs announced guard Laurent Duvernay-Tardif suffered a game-ending knee injury and Hopkins' field goal made it 10-0 through the first three possessions.

The loss of Duvernay-Tardif was notable, since Football Outsiders ranked the Chiefs' offensive line 31st in the league in pass protection through Week 3. As a result, Smith consistently needed to buy time with his mobility as his pocket broke down but found his footing in Kansas City's final two possessions of the half.

He capped a seven-play, 73-yard drive with a 17-yard touchdown strike to Kelce after Washington announced Josh Norman suffered a rib injury. The Chiefs still trailed 10-7 at the half following Butker's missed field goal.

There was no missed-kick hangover, as the Chiefs seized the lead with a dominant drive out of the locker room. Smith demonstrated his dual-threat capabilities again when he found Kelce despite a roughing-the-passer penalty to move into the red zone before he scored the go-ahead touchdown with his legs.

Will Brinson of CBS Sports didn't hold back his praise after a drive that featured Smith, Kelce, Hunt and Tyreek Hill:

Cousins missed the memo about the Chiefs being the league's best team when he answered with a 69-yard connection to Vernon Davis and touchdown pass to Grant on the ensuing possession.

However, it was the last time Washington found the end zone, as Butker's three late field goals and Kansas City's defensive touchdown on the final play sealed the game.

Washington can at least take solace knowing the next two weeks will be light with a bye in Week 5 and a date with the winless San Francisco 49ers in Week 6. The Chiefs will face the 2-2 Houston Texans in a potential playoff preview in their Week 5 contest.