OSLO: A day after turning 20, D Gukesh rediscovered both his spark and his smile, defeating compatriot R Praggnanandhaa in a gripping classical battle to pocket three full points and reignite his campaign in Norway Chess here.
Reigning champion Magnus Carlsen's woes deepened as he lost to American Grandmaster Wesley So, leaving the world No. 1 at the bottom of the six-player standings after five rounds.
The victory lifted So to second place on 8.5 points, behind tournament leader Alireza Firouzja, who maintained his grip on the top spot with 10 points and has so far dominated the field.
For Gukesh, now on 6.5 points and in sole third place, the victory seemed to breathe life back into the venue.
Fans, who had packed the arena, flocked around the world champion for autographs, selfies and photographs, while Gukesh himself appeared far more relaxed after a difficult few days in which he had often slipped quietly out of the playing hall following disappointing results.
Praggnanandhaa, on six points, remained fourth, while German Grandmaster Vincent Keymer was fifth on five points. Carlsen, meanwhile, found himself in the unfamiliar position of last place with 4.5 points.
For Gukesh, another classical victory in Round 6 and a Firouzja loss could put him within striking distance of the lead.
The all-Indian showdown was a roller-coaster, with momentum swinging repeatedly between the two players. Both enjoyed winning chances, but in the end it was Gukesh who held his nerve when it mattered most.
The game, arising from a Ragozin Defence, initially appeared to favour Praggnanandhaa despite the engines showing little separation.
Yet Gukesh remained unfazed, even making his first visit to the confessional booth and displaying little concern about his position.
A tense battle turned into a time scramble as both players raced through the critical phase around move 40 with only seconds to spare. Amid the mounting pressure, Praggnanandhaa's made a costly blunder and handed Gukesh the opening he needed.
The world champion pounced decisively, converting the opportunity into a swift checkmate attack.
Gukesh summed it up as "just a very complex game," adding with a smile, "Luckily, the tricks kind of worked out for me."
"I felt a lot of pressure and was very tense from the start, but I'm lucky to have come through. I'm surely doing much, much better than I was a couple of months back. I feel much sharper. The results are improving, though they are still not where I want them to be. But I believe that if I continue playing good chess, success will come," said Gukesh.
"When you're happy, you feel good about yourself. You feel confident and sharp over the board, and you automatically trust yourself to make quick, good decisions. They may seem like minor things, but at the end of the day, they make a big difference," added the world champion.
By toppling Carlsen, So kept the title race alive -- another such win would make him the only player capable of drawing level with the leader.
After a day spent on a speedboat, young Indian women's World Cup winner Divya Deshmukh brought the same pace to the board, outplaying China's Zhu Jiner in a classical game to claim three points and surge to the top of the six-player standings for the first time on 8.5 points.
Divya appeared to be on the back foot after Zhu introduced a fresh idea in the opening, but the game soon veered into uncharted territory.
Trusting her instincts, the Indian repeatedly found resourceful moves to stay in the fight as the balance gradually shifted. Zhu failed to seize a key opportunity to force a draw, allowing Divya to seize the initiative.
With both players eventually scrambling on the 10-second increment, Divya's relentless pressure paid off, culminating in a hard-earned 84-move victory that propelled her into sole lead.
Open: Alireza Firouzja (FRA) 10 bt Vincent Keymer (GER, 5); Magnus Carlsen (NOR, 4.5) lost to Wesley So (USA, 8.5); R Praggnanandhaa (IND, 6) lost to D Gukesh (IND, 6.5).
Women: Zhu Jiner (CHN, 5) lost to Divya Deshmukh (IND, 8.5); Anna Muzychuk (UKR, 7) bt Bibisara Assaubeyeva (KAZ, 8); Ju Wenjun (CHN, 5) lost to Koneru Humpy (IND, 4.5)