Defending world champion D. Gukesh pulled off a major upset on Thursday, defeating World No. 1 Magnus Carlsen in the sixth round of the Grand Chess Tour SuperUnited Rapid 2025 in Zagreb, Croatia.
The emphatic win propelled the 19-year-old Indian into sole lead of the tournament with 10 points.

Gukesh, who shared the lead after the opening day, extended his dominant form by outplaying Uzbekistan's Nodirbek Abdusattorov and American Grandmaster Fabiano Caruana in the fourth and fifth rounds, respectively. The stage was then set for a high-stakes showdown with Carlsen-one Gukesh approached with steely composure.
In contrast, Carlsen appeared dismissive ahead of the encounter, stating he would treat the game "as if I'm playing one of the presumably weaker players." Gukesh made him regret those words, showcasing tactical precision in the rapid format to outplay the Norwegian and hand him a rare and decisive loss.
"It's nice that I could win two games in a row from losing positions - and against Magnus," Gukesh said after the match.
This clash marked the first of three scheduled meetings between the two during the event, with the remaining encounters set to take place in the blitz section.
Carlsen, after the defeat, admitted that he was convincingly beaten by his Indian counterpart.
"I've played poorly. This time, I got soundly punished. Honestly, I am not enjoying playing chess at all right now. I don't feel any flow at all when I'm playing, I'm constantly hesitating and it's just really poor right now," Carlsen said after the match.
"I was pretty hopelessly lost. It was poor but all credit to Gukesh as he is playing well and taking his chances. He is doing incredibly well, and winning five games in a row is no easy feat," he added.
Gukesh's fifth straight win gives him a two-point cushion heading into the final day of rapid chess, positioning him as the clear frontrunner for the title in Zagreb-and sending a strong signal that the balance of power in elite chess may be shifting.