Anand found his feet with the black pieces in game 3, defending accurately against Topalov (pictured) for a draw.
Now Anand gets his turn with the white pieces again and a chance to gain the initative in the match.
Game 4 starts at 12:00 GMT on 27 April and there will be free live coverage (to all membership levels) of the game at Chess.com TV from Sam Shankland and David Pruess.
UPDATE: ANAND WINS GAME 4 TO TAKE THE LEAD 2.5-1.5!!!
Game 4 is below with analysis by GM Magesh Panchanathan!
"Not another Catalan!". Topalov feels the heat against the champion Anand (pic from the official site)