Despite more rain on day six, the slow-burner tournament began to heat up with women's second seed Aryna Sabalenka, two-time champion Petra Kvitova and last year's runner-up Ons Jabeur all reaching the last 16.
In the men's draw, third seed Daniil Medvedev and fifth seed Stefanos Tsitsipas both swept through while 2021 runner-up Matteo Berrettini set up a showdown with Alcaraz.
World number one Alcaraz has raised expectations sky high after his title at Queen's Club last month and a showdown next Sunday against seven-times champion Novak Djokovic is already being pencilled in by many.
What is sometimes forgotten, however, is that the Spaniard is playing just his fourth tournament on grass.
That showed at times against Chile's Nicolas Jarry as he was pushed out of his comfort zone.
But despite at one stage heading towards a fifth-set decider, he managed to land the telling blows when required to emerge with a 6-3 6-7(6) 6-3 7-5 victory on Centre Court.
With the big-serving Berrettini up next, Alcaraz, who was a break down in the fourth set, said Saturday's test was just what he needed.
"This match made me a lot of confidence honestly. Every match that I win on Centre Court is better for me to get into this court, this atmosphere," he told reporters.
Berrettini, unseeded after a season plagued by injury, looked razor-sharp as he beat former world number two Alexander Zverev in a high-octane Court One clash which ended under the roof after rain fell late on Saturday.
SEISMIC FOREHANDS
His 6-3 7-6(4) 7-6(5) defeat of the German 19th seed included 15 booming aces and umpteen seismic forehands as he made up for lost time after missing last year's tournament because of a positive COVID-19 test.
"I honestly don't know. It feels unbelievable. It is something I didn't think could happen. It must be something special about this place," the 27-year-old Italian said.
Medvedev, seeded three, dropped his first set of this year's tournament but is in the fourth round for only the second time after downing Hungary's Marton Fucsovics 4-6 6-3 6-4 6-4.
And the Russian is beginning to fancy his chances on a surface that has proved tricky for him in the past.
"Even I wouldn't say that I love grass, I feel like I can play well here," Medvedev, who was banned along with the other Russian and Belarusian players last year because of Russia's invasion of Ukraine, told reporters.
"So that's important for me to try to prove to myself and maybe everyone else that I can do it and can go far."
Rybakina ensured a demoralising 48 hours for Britain as she demolished Katie Boulter 6-1 6-1 to end home hopes in the singles. On Friday, Andy Murray, Cameron Norrie and Liam Broady all exited the men's singles.
With Rybakina suffering with a virus at the French Open and having a disrupted preparation, British number one Boulter was tipped to cause a huge third-round shock.
But she lasted only 57 minutes as Kazakhstan's Rybakina sent out an ominous warning to those wanting her title.
Next she will face Beatriz Haddad Maia who beat Sorana Cirstea 6-2 6-2 and who is aiming to become the first Brazilian woman to reach the last eight here since the great Maria Bueno in 1968.
Second seed Sabalenka is also in the groove heading into the second week after a 6-2 6-3 defeat of Anna Blinkova.
Sixth seed Jabeur, desperate to make up for last year's near miss, was in trouble against Canada's Bianca Andreescu a former U.S. Open champion, but found a way to a 3-6 6-3 6-4 win to set up a last-16 clash with Kvitova.
Kvitova, bang in form on grass after a title run in Berlin last month, beat Serbia's Natalija Stevanovic 6-3 7-5.
The match of the day saw Denmark's eye-catching 20-year-old Holger Rune, seeded six, delight a packed Court Three crowd as he saved two match points to beat Spain's Alejandro Davidovich Fokina 6-3 4-6 3-6 6-4 7-6(8).
Rune battled back from 5-8 down in the final-set tiebreak and was helped at 8-8 when his opponent bizarrely sent in an underarm serve which Rune demolished for a winner.
"It was obviously surprising but I don't think he even bounced the ball, so I was, like, I was aware that something was different," Rune told reporters.
Big-serving American Christopher Eubanks continued his fairytale progress as he won three tiebreaks against Australian Chris O'Connell, taking his ace count to 72 for the week.
He will next face Tsitsipas, who beat Serbian Laslo Djere 6-4 7-6(5) 6-4.
