It was a good day for the underdogs/those who were trailing, as none of them lost ground on their opponents - though in every case they started off on the wrong foot.
Thus Veselin Topalov started off with a loss as Black against Hikaru Nakamura, but struck back in the next game. The same pattern happened in the next two games, with first Nakamura and then Topalov again winning with Black. The last two games were drawn, and so while they split the 10-minute games 4-4 (or rather, 12-12 on the 3-1.5-0 scoring used for the 10-minute portion of the match) Nakamura keeps his hefty overall lead, 40.5-27.5 going into the last day.
Fabiano Caruana came into the day four points behind Alexander Grischuk - the difference provided by the latter's win in the final game in the g/20 portion of the match. It looked like it was about to become a blowout in the g/10 after Grischuk scored 3.5 points in their first four games, thanks in part to his own successful play but also due to some egregious blunders by Caruana. But Caruana righted the ship, winning three games in a row before drawing the last game, so Grischuk maintains his 4-point lead (36-32) heading into the finale.
Wesley So came into the day with a significant deficit against Leinier Dominguez, and after four draws and a loss in the game/10 portion it looked like the match was as good as over. But not yet! So won the last three games of the day, and trails 37.5-30.5.
Sunday's action comprises 12 five-minute games, each worth two points (2-1-0 scoring), so none of the matches have been clinched yet (though Topalov's chances of coming back are extremely low).
The fourth match started today, and will continue through Tuesday: Magnus Carlsen vs. Ding Liren. They played four 30-minute games, drawing the first three before Carlsen won and took the lead in game four. Carlsen had White in games 1 and 3, but should have lost that first game. He was bailed out, and then Ding was bailed out in game 3 when he too was entirely lost. Carlsen's win in game 4 was impressive, pressuring his opponent in a nominally equal ending until he broke. Following the pattern of the earlier matches, they will play six 20-minute games tomorrow.