Top seed Novak Djokovic defeated 14th seed Jo-Wilfried Tsonga to move into the Wimbledon quarterfinals.
The 2011 champion dominated the opening two sets before the Frenchman rallied to take the third to a tie-break, succumbing 6-3 6-4 7-6 (7-5).
Djokovic will next face Marin Cilic after the Croat beat Jeremy Chardy to make his first Wimbledon quarter-final.
Grigor Dimitrov, the 11th seed, will meet Andy Murray in the last eight.
The Bulgarian held his nerve in a rain-interrupted match to see off Argentine Leonardo Mayer 6-4 7-6 (8-6) 6-2 and book an attractive-looking quarter-final date with the defending champion.
Djokovic has won all nine of his previous matches with Cilic, who beat Chardy 7-6 (10-8) 6-4 6-4, but is wary of underestimating an opponent who ousted sixth seed Tomas Berdych in the third round.
Australian Open champion Wawrinka wasted little time wrapping up a 6-3 6-3 6-4 victory in 86 minutes.
Spaniard Lopez beat big-serving ninth seed John Isner 6-7 (8-10) 7-6 (8-6) 7-6 (7-3) 7-5 despite the American hitting 52 aces.
Nishikori was level at 3-3 in the fifth set with Italian lucky loser Simone Bolelli when play was suspended on Saturday, and he went on to complete a 3-6 6-3 4-6 7-6 (7-4) 6-4 win over the world number 45.