He remains a strong favourite - alongside rival Federer - to go all the way to Sunday's final.
Being made to play his fourth round and quarter-final matches on successive days cost Djokovic dear last July as he not only ended up retiring hurt from in his last-eight contest but also had to call time on his 2017 season.
Federer took his tally of consecutive sets won on London's hallowed lawns to 32 with a 6-0 7-5 6-4 dispatch of unsafe French left-hander Adrian Mannarino.
Mannarino won only two points in the first five games and the opening set was brought to an end inside just 16 minutes.
He has also lost all four meetings against the 20-time major victor, failing to win a set off the great Swiss star. "It was dark so I couldn't see the ball that well and it was very windy".
The Swiss is two sets short of his all-time record streak, which he set between the third round in 2005 and the final in 2006.
"You can't plan for them anyway".
Victory for Nadal over his fellow left-hander would take him into a 35th Grand Slam quarterfinal.
And all on a surgically-repaired knee. A former world number 15, she talked about retiring previous year, saying that tennis "just wasn't fun" any more and that her main goal in 2018 was to feel good. "That it happened to be in straights, it helps me for to save energy for the rest of the tournament".More news: Tropical Storm Chris to bring showers
The action has continued on day eight at Wimbledon, aka "Manic Monday" with Serena Williams powering her way past fellow tennis mum Evgeniya Rodina while Rafael Nadal accounted for Jiri Vesely to make the first quarter-finals at the tournament for the first time in seven years.
Three-time champion Djokovic, seeded 12, will next face Japan's 24th seed Kei Nishikori.
Tsitsipas, whose Greek father and Russian mother are both tennis coaches, had set a goal at the beginning of the year of reaching the fourth round of a Grand Slam tournament.
He added: 'There's a good chance it's going to come down to a few points here and there. Is true has been a while since I have been in that position. Djokovic reached his 41st career major quarterfinal, tying Jimmy Connors for second all time. "It was a really high quality match, I had to dig deep", Anderson said after the match. "These are the matches we work so hard for, me and my whole team". That, of course, is a positive result. "But it was more about (the fact that) I was not able to compete at the best level".
"But things are looking much better in the last month and a half".
It would also give him a last-eight clash against Juan Martin del Potro, the fifth-seeded Argentine, or unseeded Gilles Simon of France. Del Potro was leading 7-6 (7/1), 7-6 (7/5), 5-7 when his tie with Simon was halted for the night due to darkness.
Twenty years ago, Federer, then an impetuous racket-smasher and AC/DC aficionado, provided a portent of what was to come by winning the junior title with a 6-4, 6-4 triumph over Irakli Labadze.
Nishikori overcame a right arm injury to reach his first Wimbledon quarterfinal with a gritty 4-6, 7-6 (7/5), 7-6 (12/10), 6-1 win over Latvian qualifier Ernests Gulbis.