Alcaraz headed into the Laver Cup as the most accomplished player taking part, but just how high a level he'd be able to produce was uncertain. The Spaniard was out from April to the end of August with an injury, and then lost to Ben Shelton in the US Open quarter-finals on his return.
However, he treated the crowd in London to some of his glorious best in a 6-3, 4-6,13-11 win over Fritz, including signature drop shots when match point down and match point up in the dramatic final tiebreak.
While he was a point away from losing, he said he was happy with the level he played at after the match, and glad to get the chance to try some new things.
"I'm just really happy to be able to play these kinds of matches, to see what my level is and see what I have to improve," he said in the post-match press conference. "I took a couple of things that I really wanted to put to practice"
"But yeah, I'm just leaving the court really, really happy with everything I've done, and obviously with the things that I've been practising so far, I did pretty well today."
In fact, the 23-year-old - feeling particularly good about a new serving approach - thinks that he's getting back to his best.
"Slowly, I'm getting back to my normal rhythm, to my normal level, in terms of tennis-wise and physically," he said.
"The serve has been a really important point for me, so I've been practising a lot and made a couple of small changes that, as far as I could see, nobody noticed, which is great. So it's been working out."
While it was his trademark flair that won him the big points at the end of the clash, Alcaraz also put his victory partially down to advice during the match from teammate Ruud to be more patient and play things safer at times.
"He was telling me, from the outside, that I had to be more calm," said the Spaniard.
"Sometimes it feels really stressful, and I (feel like) I have to overplay and play big; all the shots all the time, that I don't need to.
"And from the outside, (he was) approaching the bench and telling me they were seeing the match in a totally different way to what I was seeing, telling him how to be more patient because I was better than him, hitting better shots than him. So I had to play some more, not overplay, and try to get into the rhythm.
"Having that advice from a player like him, it was really meaningful and really helpful for me."