Daniil Medvedev tossed in an opportunistic underhand serve in the late stages of his 6-3, 6-4 defeat of Alexander Zverev as the Russian won his first career match at the ATP Finals on Monday.

Medvedev earned a point in the penultimate game with his surprise underhand delivery against the 2018 champion here.

Medvedev lost all three of his group matches in London a year ago in his career year-end debut.

“I didn’t want to disrespect him, so I made the underhand serve at 30-all (leading a set and 4-3 in against the German),” Medvedev said.

“I saw he was five metres behind the baseline and I had the ball close to my racquet so I just went for it just to try and win the point.

“I’m happy that it worked – that was smart.”

Medvedev beat Zverev eight days ago to win the Paris Masters title and proved his point with the repeat victory in a stadium left empty due to COVID-19 quarantine rules.

Both men got off to poor starts, with Zverev committing six doubles faults in the opening set – including three in a disaster of a second game.

London 02 Arena Nitto ATP Finals Day 2 Tokyo 1970 Group Round Robin Match Daniil Medvedev (RUS) beats Alexander Zverev (GER) Roger Parker International Sports Fotos Ltd

Medvedev saved five of six against his serve and broke his opponent twice. The momentum changed in the second set, with a break in the seventh game enough to see the Russian through.

 “Confidence after beating him in Paris was a key for sure,” Medvedev said. “Winning a Masters 1000 title helps.

“I knew I would play good in this match, it was one of the most intense I’ve ever played.

“In the second set I could see he was exhausted – and so was I. So we just fought on.

“Facing another Top 10 player, you have to be there for every point, stay focused.

“I was happy to win this battle.”