LONDON (AFP) - Dominic Thiem recovered from squandering four match points in a dramatic second-set tie-break to beat Novak Djokovic in the last four at the ATP Finals on Saturday (Nov 21).

The US Open champion won 7-5, 6-7 (10/12), 7-6 (7/5) and will face either Rafael Nadal or Daniil Medvedev in Sunday's final at the elite eight-man event.

The world's top four players all made it through to the semi-finals for the first time at London's O2 Arena, which is hosting the season-ending event for the 12th and final year.

Thiem forced the only break to take a tight first set 7-5 but neither player could make the breakthrough in the second set, which went to a tie-break.

Thiem had four match points but agonisingly watched them all slip away as 17-time Grand Slam champion Djokovic levelled.

It was a similar story in the third set, with both players rock-solid on serve and the match came down to a deciding tie-break.

The Serbian world number one raced into a 4-0 lead and looked certain to win but Thiem stormed back, winning six points in a row to earn two more match points.

He was unable to capitalise on the first of those but won the second to take the match.