Novak Djokovic’s fate in the ATP Finals hangs in the balance despite his win over Hubert Hurkacz on Thursday.
Djokovic defeated Poland’s Hurkacz, a replacement for the injured Stefanos Tsitsipas, 7-6 (7-1) 4-6 6-1 in Turin.
However, the world number one will not qualify for the semi-finals if Holger Rune beats Jannik Sinner in the final group game later on Thursday.
Italy’s Sinner, who ended Djokovic’s 19-match winning streak on Tuesday, is guaranteed a place in the last four.
The 22-year-old home favourite, who will finish at least second in the Green Group, is set to become the first Italian to play in the semi-finals of the season-ending tournament.
Unable to progress regardless of the result, Hurkacz came into the match against Djokovic with nothing to lose and held firm on his serve throughout the first set.
The world number nine crumbled in the tie-break and Djokovic needed just the second of six set points to secure the opener.
However, in a 14-minute period where the Serb failed to win a single point, Hurkacz broke and consolidated to go 4-2 up before saving two break points and serving out for the set.
Djokovic regained control to secure the third set and the match, but he requires Sinner to beat Rune if he is to continue his bid for a record seventh ATP Finals title.
The ATP Finals features eight of the year’s best men’s players split into two groups of four, with the top two in each qualifying for the semi-finals.