Dominic Thiem has edged World No.2 Novak Djokovic in a classic contest at the ATP Finals in London to seal an incredible victory and a place in the semifinals 6-7(5) 6-3 7-6(5) after two hours and forty-seven minutes.
The two men thrilled the audience inside the O2 Arena with their relentless pursuit to outwit each other, there was no room for errors as it became an opportunity for the other to pounce on. This high intensity battle finally had to be settled in dramatic third set tiebreak.
Djokovic drew first blood by showing strong resolve in the opening set tiebreak to go one up. Thiem did not let his guards down as he came out of the blocks with an early break in the second set, an advantage he held to peg back and force a decider.
The Austrian carried the momentum into the decider and earned an early break. He showed more grit by saving three break points to consolidate his advantage. As always, Djokovic kept probing and got his rewards in the sixth game to level.
Both men held firm to their serves from there, momentum though had now swung to the side of the Serbian who was razor sharp with his returns in a bid to get a break but Thiem found a way round the immense pressure to stay afloat.
Djokovic faltered with four straight errors to give Thiem a love break at and a chance to serve out the match at 6-5. But the Serbian made up for it with another incredible return game to break back, forcing a deciding tiebreak.
Thiem found himself 1-4 down to Djokovic in the tiebreak, but won five straight points including two beautiful forehand winners to bring up two match points at 6-4. Djokovic saved one but the next on his service would see him send a forehand into the net as Thiem crouched down on the court to celebrate back-to-back wins against two of the greatest players of all time.
The 26-year-old completed the match hitting 51 winners, 72 percent points won on his first serve and 49 percent on second serves.
Earlier on Tuesday, Roger Federer opened his account with a 7-6(2) 6-3 win over Matteo Berrettini. The Swiss will face off with Djokovic in a shoot-out where the winner joins Thiem in the semifinal.
The second Round Robin matches in Group Andre Agassi will be played on Wednesday with World No.1 Rafael Nadal taking on Daniil Medvedev. Stefanos Tsitsipas will play against defending champion Alexander Zverev in the night session.