FOXBOROUGH, Mass. -- Patrick Mahomes played his worst half of the season in the first 30 minutes on Sunday night against the New England Patriots, throwing two interceptions that put the Kansas City Chiefs far behind.

He didn't get rattled. He instead turned the game into a classic duel in his first showdown with New England's Tom Brady.

"When you have the guys I have on this team with the weapons that I have,'' Mahomes said, "I have to keep slinging it.''

That's what Mahomes did. He threw four second-half touchdown passes, three to Tyreek Hill, in leading the Chiefs back from their 15-point halftime deficit.

Brady beat Mahomes in the end. The Patriots kicked a walk-off field goal to win 43-40.

Finally, Mahomes came across an opponent he couldn't outscore. Brady and the Patriots got it done, though Mahomes made them work for it.

"He made a lot of big [throws],'' Brady said. "Tough to slow those guys down. They're going to be pretty tough to stop. So glad we had our last shot and glad we took advantage of it."

Mahomes and the Chiefs are 5-1 this season. They are 6-1 with Mahomes as their starting quarterback, counting the final regular-season game against the Denver Broncos last year. In that game, Mahomes led the Chiefs to a walk-off field goal and a 27-24 victory.

Sunday's game didn't start well for Mahomes. He put the Chiefs in bad spots in the first half for the first time with his two interceptions. One put the Patriots on the Kansas City 4-yard line, and they took advantage of the favorable field position for a touchdown. The other, in the red zone near the end of the second quarter, cost the Chiefs at least three points.

"I missed some throws,'' Mahomes said. "That happens in this league. But whenever you're playing good football teams, you can't miss those throws. We left some points out there.''

But he kept firing and was rewarded with the four touchdown passes, including one of 67 yards to Kareem Hunt and another of 75 yards to Hill.

"We just starting hitting on throws that I was missing earlier,'' Mahomes said. "I feel like we moved the ball well the entire night. We just have to find ways to score in the red zone. The last two weeks, it just seems like we can't punch it in there, and I feel like in the second half, we finally started getting it in the end zone.''

Brady and Mahomes wished each other well at midfield after Stephen Gostkowski's 28-yard field goal decided the game. The game might have been only the opening chapter of their rivalry.

"He gave me congrats on playing a good game, and of course I did the same to him,'' Mahomes said. "I just kind of told him good luck for the rest of this season. We're going to go out there, and hopefully we can keep playing, and hopefully we might be able to see him again.''