Rafael Nadal officially reclaimed his standing among the 'Big Four' on Monday, while Tomas Berdych and Marin Cilic moved up the ATP World Tour rankings.
Nadal's run to the Monte Carlo Masters semi-finals, where he was beaten by world number one Novak Djokovic, saw him eke back into fourth spot ahead of Kei Nishikori, who dropped to fifth.
Nadal spent two weeks in fifth place, the first time he dropped out of the top quartet since June 2013.
Monte Carlo Masters runner-up Berdych replaced David Ferrer in seventh, while Cilic moved one spot to ninth at the expense of Stan Wawrinka - who was ousted in the last-16 of his Monte Carlo title defence.
Gael Monfils moved up three spots to 15th - his equal-highest rank since May 2012 - and reaching the semi-finals in Monte Carlo.
Juan Monaco (up six to 36th) was another positive mover, while Nick Kyrgios (down seven to 41st) and Guillermo Garcia-Lopez (down 12 to 45th) were the big losers in the top 50.
Lucas Pouille, a 21-year-old from France, was a first-time top-100 entrant, his points gained from reaching the second round in Monte Carlo - where he lost to eight-time champion Nadal - taking him to 98th in the world.
Serbia's Filip Krajinovic (down 10 to 102nd), Belgian Ruben Bemelmans (down two to 101st) and Nicolas Almagro (down 23 to 123rd) dropped out of the top bracket.