After three weeks, 12 straight draws and a day of tiebreakers, Norway’s Magnus Carlsen finally retained the world chess championship in London on Wednesday with a victory against Fabiano Caruana, his American challenger.

Carlsen’s victory came in what amounted to sudden-death chess: a scheduled series of four so-called rapid games in which the players started with 25 minutes to make their moves. The speedier pace of the games, after the far more deliberate matchups of the previous three weeks, meant players were more likely to make blunders. And that increased the chance of a victory by one player.

Carlsen won the first two games, then closed out Caruana in Game 3.

“Everything kind of went perfectly,” Carlsen said.

In Game 1, Carlsen, playing white, quickly seized control of the center and, after a flurry of exchanges, wound up with a pawn advantage. For the first time in the match, he was able to turn the edge into a win; Caruana resigned after 55 moves.