Daniil Medvedev reached the semi-finals at the ATP Finals and Carlos Alcaraz kept alive his own hopes on his debut by beating an anguished Andrey Rublev.
Wimbledon champion Alcaraz had lost to Alexander Zverev in his Red Group opener but the Spaniard returned to beat Rublev 7-5 6-2 in Turin, Italy.
Rublev hit himself so hard with his racquet that he drew blood in a loss that ended his last-four chances.
But fellow Russian Medvedev beat Zverev 7-6 (9-7) 6-4 to reach the semi-finals.
In the doubles, Britain's Joe Salisbury and American Rajeev Ram - the defending champions at the prestigious season-ending event - advanced with a match to spare.