The lone rest day in the Brazilian leg gave enough time to Anand to recover from an unexpected loss in the third round against Vassily Ivanchuk of Ukraine.
Although Anand's opponent Vallejo was near to a draw, the Indian's skills proved far superior.
Meanwhile, Ivanchuk took another giant leap forward by defeating Levon Aronian of Armenia.
With his third victory on the trot in the category-22 super tournament being played under a soccer-like scoring system, the 42-year old Ivanchuk (10 points) stretched his lead to a huge 5 points over nearest rivals Anand and Aronian.
The other game of the day between world number one Magnus Carlsen of Norway and Hikaru Nakamura of United States ended in a draw, leaving the latter at fourth spot with four points, while Carlsen and Vallejo Pons share the last spot on three points apiece.
After losing the previous game, Anand spent the off-day having Japanese lunch and a walk in the park as he prepared himself for a comeback, which many pundits had predicted.
Vallejo Pons is the lowest ranked player in the tournament and his lone victory against Carlsen had come from a much worse position.
Anand went for symmetrical set-up in the English opening and Vallejo showed some courage earlier on by looking forward to complications. However, the world champion went for an early trade of queens that gave the indication that a long battle was well on cards.While going for the weakening of black's queen side pawn structure, Vallejo had to part with the Bishop and this gave Anand much to look forward to once the pure minor piece endgame arose.
Much to Vallejo's dismay, he found his knight gasping for breath in the heart of black's position, while Anand's king made headways through the king side.
Anand knocked down a pawn with ease and Vallejo threw in the towel after 57 moves.
Meanwhile, Ivanchuk seems to be running away. The Ukrainian has been driving through a mine-field in top gear and so far his strategy of going for extremely complicated positions has paid heavy dividends.
Aronian learnt it the hard way in a Queen's gambit declined. Ivanchuk settled down comfortably in the middle game even as white's pawns and pieces came hurtling at his king. The shocker for Aronian came on move 20, when Ivanchuk placed his queen in the center and threatened checkmate.
A temporary piece sacrifice followed and Ivanchuk almost blew it away in time scramble. However, Aronian returned the favour by blitzing away his moves even though he had more time. Ivanchuk won in 38 moves.
Carlsen and Nakamura also discussed a Queen's gambit declined but in a much peaceful way. Carlsen secured a microscopic advantage in the opening but Nakamura was on his guard throughout and converted to a level queen and minor piece endgame. The draw came with perpetual checks.
Results round 4: Francisco Vallejo Pons (Esp, 3) lost to V Anand (Ind, 5); Levon Aronian (Arm, 5) lost to Vassily Ivanchuk (Ukr, 10); Magnus Carlsen (Nor, 3) drew with Hikaru Nakamura (Usa, 4).