Stefanos Tsitsipas has defeated Daniil Medvedev 7-6 (7-5), 6-4 to reach his first win in the group stage of the ATP finals.

The 20-year-old has now become the first Greek to not only feature in the competition, but to also claim a victory.

Tsitsipas had never won against the world number four (who was also in his tournament debut), but this time demonstrated a lot of patience in the build up of his game and was determined to walk away with the win.

The Russian wasn’t willing to go down easily and the two aspiring tennis stars gave everything they had in the first set, which was decided at the tie-breaker (6-6).

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But it was there that Tsitsipas proved that this time, things would be different than in their previous meetings, as he maintained a level head and broke Medvedev’s serve to claim an important win.

The loss of the first set had a negative impact on the Russian, who tried to make a comeback but couldn’t keep up in the second set, with Tsitsipas breaking away from early on to end up with a comfortable win (6-4) and his first ever victory in the competition.

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Meanwhile, the upset came from Alexander Zverev, with the young German walking away with a comfortable win against Rafael Nadal, 2-6, 4-6.

Both these results could play a huge impact on the world number six’s future in the tournament, as he prepares to take on Zverev this Thursday for round two of the group stage.