TURIN, Italy (AFP) — Alexander Zverev battled back from a set down to beat Carlos Alcaraz 6-7 (3/7), 6-3, 6-4 at the ATP Finals on Monday while Daniil Medvedev won a Russian derby against Andrey Rublev in straight sets 6-4, 6-2.

Germany's Zverev, a two-time winner at the year-ending tournament, put on a powerful display to see off world No. 2 Alcaraz who is not on top form after returning from injury at the end of last month.

Zverev is tough opposition on hard courts like the one at the Pala Alpitour in Turin and made full use of his height and power in the Red Group clash to see off Alcaraz, who looks far from being the ageless Novak Djokovic's main rival for the title.

The 26-year-old Zverev rattled off 16 aces and was only broken once over the course of an impressive win in which he hit more winners and made significantly fewer unforced errors than out-of-sorts Alcaraz.

"In the beginning of this year, I was nowhere near his level," Zverev told reporters.

"I'm just happy to be back at the level where I'm competitive with those guys, where I feel like I can win, I feel like I can compete for tournaments again."

Wimbledon champion Alcaraz has struggled with lower back and left foot problems which had kept him out of action since the Shanghai Masters in early October until the Paris Masters.

He was dumped out early in the French capital by Russian qualifier Roman Safiullin and flagged towards the end of a bruising contest with giant Zverev, the number seven seed in Turin.

Alcaraz, however, insisted that he was not struggling back to form after his lay-off.

"I'm one of the players who has played most matches on tour. I feel good physically," Alcaraz said.

"I don't think I need more matches (to be in top condition)."

Before Zverev's win, Novak Djokovic was presented with the trophy for finishing the season as world No. 1.