A rain delay saw the match delayed overnight with Cilic two sets to the good but he failed to find his rhythm as the Argentine won 3-6 1-6 6-4 6-4 7-5 to reach the third round of a major for the first time.
German fourth seed Alexander Zverev made the third round, seeing off Taylor Fritz of the United States 6-4, 5-7, 6-7 (0/7), 6-1, 6-2 and faces Latvian qualifier Ernests Gulbis for a spot in the last 16.
But the Croatian collapsed once the match resumed on Court One on Thursday and Pella took full advantage to set up a third round clash with Mackenzie McDonald.
The scoreboard said 6-4 6-3 6-4 to Rafael Nadal but it was an uneasy two-and-a-half hours for the Spanish world number one as he labored past Kazakhstan's Mikhail Kukushkin into the Wimbledon third round on Thursday. It was a very nice surprise to me.
The 11-time French Open champion is looking for his third title at the All England Club and first since 2010.
"I didn't know but I don't see a clock here".
Djokovic hit 15 aces and 31 winners in a commanding win over 33-year-old Zeballos, who was a top 40 player in 2013 but was playing at Wimbledon ranked a lowly 126.
Cinematographer may have leaked title of 'Avengers 4'
Actor Chris Hemsworth earlier said that the fans will find Avengers 4 more shocking than its predecessor Avengers : Infinity War . End Game could possibly refer to Doctor Strange's conversation with Iron Man as he states, " We are in the end game now".
The world number 133 is in the third round for the first time after winning back-to-back matches on the main tour for only the second time in 2018. Yet hopes that Kyrgios would face another Australian next were dashed after Bernard Tomic lost 2-6, 6-3, 7-6 (7), 7-5 to Kei Nishikori, the 24th seed.
The Kazakh, with a curious undercut double-handed backhand and some clever angles, broke back to level at 3-3 though before Kukushkin wobbled when serving at 4-5.
The 36-year-old American now can not meet a top 32 player until the semi-finals after the scattering of the seeds this week.
Del Potro faces Benoit Paire in the third round after the Frenchman upset 26th-seeded Canadian Denis Shapovalov.
Raonic, if he remains fit, is probably the most likely to meet the 20-time Grand Slam champion at that stage - a match the 2016 runner-up won at the same stage two years ago.
Guido Pella of Argentina took out last year's beaten finalist Marin Cilic of Croatia in the second round at Wimbledon.
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