Novak Djokovic booked a place in the semi-finals of the ATP Finals by beating Russian Andrei Rublev 6-3 6-2 on Wednesday, while Stefanos Tsitsipas withdrew due to an elbow injury.
ATP said the Greek player in fourth place in the world, who won the championship in 2019, is suffering from an injury to his right elbow.
The same pain caused Tsitsipas to withdraw from the Paris Masters earlier this month, with Britain’s 12th-seeded Cameron Norrie taking place in Turin, Italy.
Djokovic, who won his opening match against Kasper Road on Monday, appeared early in trouble in his first ever match against Rublev when his serve was broken in the first half.
The Serb, hoping for a sixth title at the WTA final, recovered quickly after Rublev’s double serve.
The sparring continued until the eighth match, where Djokovic broke the serve to win the first set.
The world number one emerged with more confidence in the second set, forcing his Russian opponent to make costly mistakes to achieve his 40th victory in the 68-minute final, ending the confrontation with an ace.
Djokovic, 34, who has won 20 Grand Slam titles, leads the green group with two wins in two matches and confirmed his arrival at the Golden Square.
Nouri will play his first match in the tournament against Norwegian Roode later today.
Nouri is the second replacement to join the tournament after Matteo Berrettini withdrew on Tuesday due to a stomach injury to replace his Italian compatriot Yannick Sener.