Carlos Alcaraz's losing streak stretched to three matches as Alexander Zverev came from a set down to defeat the Wimbledon champion in their opening ATP Finals round-robin encounter.

Zverev came up short in a first-set tie-breaker and struggled with a foot injury during the closing stages, but the German came through 6-7[3] 6-3 6-4 in just over two and a half hours in the Red group.

In doing so, Zverev condemned Alcaraz to three successive losses for just the third time in the Spaniard's fledgling career, while also recording his fourth win from seven meetings between the pair.

Zverev - the 2018 and 2021 ATP Finals champion - traded a break apiece with Alcaraz in a pulsating first set, where the German also missed another four opportunities to break his youthful counterpart, who also squandered another three chances to do so before coming up trumps in the tie-breaker.

It was aces galore in the second set, where Zverev broke for a 2-0 lead and levelled the match on a love hold with three unstoppable first serves, before drawing first blood in the decider with a break in the fifth game.

Hearts were in mouths when Zverev slipped on the court and damaged his foot - akin to his devastating ankle injury at last year's French Open - but he managed to soldier on and gave himself the chance to serve for the match.

Alcaraz fashioned one break point as he sought to keep the tie alive, but Zverev closed the door with his 16th ace of the day before two more blistering serves did the trick, as Alcaraz sent one final tired forehand into the net.

Zverev's victory has moved to the top of the Red group ahead of Monday evening's battle between Russian duo Daniil Medvedev and Andrey Rublev.