Dubai, UAE CNN  — 

Magnus Carlsen defended his World Chess Championship crown on Friday after defeating Ian Nepomniachtchi in three hours and 20 minutes to take Game 11 and his fifth title.

The Norwegian grandmaster’s unassailable tally of 7.5 in the best-of-14 game series means he has successfully defended the crown for a fourth time. The win also means his reign as champion will extend to over 10 years by the time the next championship rolls around.

The atmosphere outside the exhibition hall at Expo 2020 Dubai, venue of the final, was feverish with anticipation that this would be the day Carlsen would claim the title.

And a blunder from Nepomniachtchi on move 23 proved crucial, eventually leaving him down a pawn going into the endgame. That was all Carlsen needed to grind out victory.

Carlsen’s father, Henrik, spoke with CNN after the game and said he’s proud but used to his son winning: “Now, it’s about seeing him as a human being and finding balance in his life.”

Russian world No. 5 Nepomniachtchi started the tournament as the underdog and proved to be a test for Carlsen in the early going. The first five rounds ended in draws, but Nepomniachtchi’s resolve seemed to break after Carlsen defeated him in a nearly eight-hour-long Game Six.

The 136-move game was the longest in world championship history and both players were noticeably exhausted after their efforts.

Carlsen’s four-point winning margin is the biggest in 100 years, according to the Guardian.

Russia's Ian Nepomniachtchi, left, and Norway's Magnus Carlsen compete.

Carlsen first became world No. 1 in 2010, and now only trails Russian grandmaster Garry Kasparov in weeks spent at the pinnacle of chess.

“I would say that Garry dominated for 20 years. And even if I were to win this championship, I would still have a way to go to reach his heights,” Carlsen told CNN before the championship started.

“And if I don’t, that will not lose me any sleep.”