Rafael Nadal was confirmed as world number one at year end after a stunning two days at the O2 Arena in London as the ATP Finals roared into life.

With Rafael Nadal having saved a match point against Daniil Medvedev in his game to come back and win, preserving his chances at progressing to the semi-finals, that impetus was felt across the groups today as Roger Federer took revenge on Novak Djokovic for his Wimbledon final defeat and knocked the Serb out at the group stage in a genuine shock.

Nadal, under pressure yesterday to win and put the pressure on Djokovic, had to save a match point, but after doing so, came back in fine style against the Russian Medvedev, who has never got closer to beating the Spanish world number one, a player the inexperienced yet impressive Medvedev has yet to overcome in his fledgling career.

With Stefanos Tsitsipas winning against Alexander Zverev in a routine 6-3, 6-2 victory, the pressure on Nadal was immense, but the Spaniard came through the challenge, eventually progressing 6-7 (3-7) 6-3 7-6 (7-4). Tsitsipas, who is making his first appearance at the finals, is now, following the matches in Group Bjorn Borg, the only man who could win the $2.8 million on offer to anyone who can go through the intense battle of the ATP Finals to victory without losing a match.