The Kansas City Chiefs (0-1) fell to the San Francisco 49ers (1-0), 27-17, in the first week of preseason action on Friday night at Arrowhead Stadium.

San Francisco rookie quarterback C.J. Beathard threw a pair of fourth quarter touchdowns to lead the 49ers to the comeback victory. With the game tied at 17 points apiece, Beathard took advantage of a Kansas City turnover with a two-yard, go-ahead touchdown pass to fullback Tyler McCloskey.

Chiefs quarterback Alex Smith completed four of six passes for 48 yards and added 10 yards on the ground in his one series of work, leading Kansas City on an eight-play touchdown drive.

Smith hit wide receiver Tyreek Hill for 32 yards down the sideline on the first play of the game before running back Spencer Ware later plowed ahead two yards for the score.

Tyler Bray took over under center following Smith's lone drive, completing five of eight passes for 63 yards and an interception. Rookie quarterback Patrick Mahomes  made his professional debut with 6:44 left in the first half and played through the third quarter, completing seven of nine passes for 49 yards and a touchdown.

Mahomes' first professional score was a one-yard strike to wide receiver Marcus Kemp with six minutes left in the third quarter.

San Francisco chipped away at their early deficit with a pair of field goals in the first half before taking the lead midway through the second quarter on a 27-yard field goal by Nick Rose. Chiefs defensive tackle Ricky Ali'ifua blocked a fourth San Francisco field goal attempt as time expired in the first half.

Kansas City retook the lead when Sam Ficken connected on a 45-yard field goal early in the third quarter and extended the lead with Mahomes' touchdown later in the quarter.

San Francisco knotted things up when Beathard hit wide receiver Kendrick Bourne for a 46-yard touchdown and converted a two-point conversion early in the fourth.

Beathard tossed the go-ahead score following Kemp's fumble midway through the fourth, setting up the San Francisco victory. The 49ers added another field goal in the game's final minutes.

The Chiefs will travel to Cincinnati next week on August 19 to take on the Bengals (1-0) at 6 p.m. in Week 2 of the preseason. Catch the game on KCTV5 or on 101.1 The Fox.