Alexander Zverev - John Isner

Alexander Zverev's 16-match winning streak came to an end at the hands of the world #1 and eventual runner-up Novak Djokovic in the semifinal at the US Open a few weeks ago — the tournament in which he finished as the runner-up to Dominic Thiem in 2020. It was still a positive performance and result for the German as he won the first set and later forced the decider against the Serbian.
World #4 Alexander Zverev has been one of the best performers so far in the second half of the season. He claimed the biggest title of his career at the recently concluded Tokyo Olympics (Gold) and followed it up by winning the title in Cincinnati Masters and a run to the semifinal at the US Open.
The 24-year-old's unbeaten record in singles matches in the Laver Cup ended at the hands of none other than John Isner in the recent edition in 2019, but he did manage to end the tournament on a high as he edged out Milos Raonic in the last match of the edition to clinch the Team Europe their third consecutive Laver Cup title.
The former ATP Tour Finals champion, who won two indoor hard court titles in 2020 and has a solid record on the surface, is yet to win a match on the surface since defeating Diego Schwartzman in the ATP Tour Finals last year. His only previous match on the surface in 2021 ended in a disappointing straight-set defeat against Alexander Bublik in Rotterdam.

John Isner is arguably Team World's best performer in the Laver Cup so far. He defeated Rafael Nadal in the inaugural edition in 2017 and Alexander Zverev in 2019 and took sets off Dominic Thiem, Alexander Zverev (in 2018), and Roger Federer.
The big-serving American made a superb start to the North American hardcourt swing by posting a couple of semifinal results in Los Cabos and Toronto Masters and claiming his first title since 2019 in Atlanta. However, he failed to register a win in his home slam at the US Open as he was stopped in straight sets by compatriot Brandon Nakashima in the first round.
Former American #1 hasn't played a match on indoor hard courts since ATP New York in February 2020 and hasn't won a match on the surface since defeating Alexander Zverev in the Laver Cup 2019.

Head-to-head: Alexander Zverev leads 6-2 (2-1 on indoor hard courts). Dominant record in the H2H series and terrific form in recent months makes the German the deserved favorite. However, John Isner is never an easy opponent to face in this part of the world, and in fact, he won at least a set in all their previous three meetings on American soil (1-2).