The Kansas City Chiefs defeated the Pittsburgh Steelers, 42-37, at Heinz Field on Sunday afternoon.

The Chiefs (2-0) piled up 42 points on 449 yards and held off a late Pittsburgh (0-1-1) rally to remain undefeated on the season.

Chiefs' quarterback Patrick Mahomes completed 23-of-28 passes for 326 yards and six touchdowns in the contest – the most in franchise history since 1964. The 22-year-old signal caller also became just the second quarterback in NFL history to begin a season with four or more touchdowns in each of his team's first two games.

Mahomes' strong outing began on Kansas City's very first drive, as he found wide receiver Chris Conley in the back of the end zone for a 15-yard score. The Chiefs went on to mount an early 21-point lead with touchdown strikes to tight end Travis Kelce and tailback Kareem Hunt on each of their next two possessions.

It all added up to the Chiefs' most first-quarter points since Week 16 of the 2016 season as Mahomes became the youngest quarterback in NFL history to toss three first-quarter touchdowns, according to CBS.

Despite the early hole, the Steelers answered Kansas City's impressive start with three scores of their own to knot the game at 21 points apiece prior to halftime – though the tie didn't last long.

Kansas City's offense turned on the jets almost immediately after the break, as Mahomes connected with Kelce for a 25-yard score just three minutes into the second half. Kelce finished the contest with a team-high seven catches for 109 yards.

Mahomes later found wide receivers Demarcus Robinson and Tyreek Hill each for scores later in the half to extend the advantage.

Steelers' quarterback Ben Roethlisberger dove ahead for a 3-yard touchdown to narrow the deficit to within one score with just under two minutes left in the game, but the Chiefs proceeded to run out the clock on their ensuring drive to secure the victory.

The Chiefs will look to continue their winning ways next week at Arrowhead Stadium against the San Francisco 49ers at 12:00 p.m. CT.