A year ago, Federer became the first man since Bjorn Borg in 1976 to win the title without dropping a set.
Federer's best run at the All England Club is 35 consecutive sets, from 2005 to 2006.
Having reached the third round at the All England Club for the seventh time, Monfils finally went a step further to complete a full set of last-16 Grand Slam appearances.
The Frenchman reached the semifinals at the 2008 French Open and the 2016 US Open. He also made it to the Australian Open quarterfinals in 2016.
Having made 13 unforced errors as he lost the opening set, the 44th-ranked Monfils made just eight more and didn't face a break point for the rest of the match.
Zverev also erased a 2-1 deficit three times to reach the quarterfinals of the French Open, his best result at a Grand Slam.
Isner hit 21 aces and never faced a break point.
This is his 10th appearance at the All England Club; he had reached the third round three other times and lost at that stage.
Isner will face No. 31 Stefanos Tsitsipas for a quarterfinal berth. Tsitsipas became the first Greek male to reach the fourth round of a Grand Slam tournament in the Open era after beating Thomas Fabbiano of Italy.
The 19-year-old Tsitsipas won 6-2, 6-1, 6-4 in 91 minutes, becoming the first Greek male to progress to Wimbledon's round of 16 since Nicky Kalogeropoulos in 1964.
"It's an amazing feeling, and I feel very proud I represent Greece and that all of my hard work has paid off,'' Tsitsipas said. "It's just such nice feelings to be the first from your country to do so.''
The 35th-ranked teenager reached his first ATP tour final this year in Barcelona, where he lost to top-ranked Rafael Nadal on clay.
The 103rd-ranked McDonald, 23, who won the 2016 NCAA singles and doubles titles for UCLA, defeated Guido Pella 6-4, 6-4, 7-6 (6) as the Argentine player featured for a third consecutive day.
"I'm in disbelief, to be honest. Just pretty crazy,'' said McDonald, who grew up in California, and now is based at the U.S. Tennis Association's main training facility in Florida. "I mean, if you told me I'd be in the second week of Wimbledon before the tournament, I wouldn't believe you.''
Pella delivered the biggest upset so far in the men's draw when he eliminated third-seeded Marin Cilic in a match that was carried over to Thursday.
Pella was unable to repeat that performance against McDonald, who is playing in his third Grand Slam. McDonald next faces 13th-seeded Milos Raonic or unseeded Austrian Dennis Novak, who is also making his Wimbledon debut. Their match was suspended due to fading light, the only singles match on Friday that didn't finish.
Play was halted with Raonic ahead 7-6 (5), 4-6, 6-5. Novak will be serving when they resume Saturday.
Information from The Associated Press was used in this report.