Venus Williams gained revenge for her Wimbledon final defeat by Garbiñe Muguruza when the American advanced to the last four of the WTA Finals with a gutsy 7-5, 6-4 victory over the Spanish world No2.
Both players knew a win would secure a passage to the semi-finals as they held identical 1-1 records in White Group at the season-ending event but the 37-year-old was stronger on the key points and moved brilliantly around the court to progress.
Muguruza had brushed aside Williams to claim her second grand slam title in Julybut any hopes she had of repeating the feat were snuffed out by a resolute opponent, who simply refused to buckle in the tense Singapore Indoor Stadium encounter.
“I played an amazing opponent who has had an amazing year so I was so happy to win the last point,” Williams said.
The victory enabled Williams, who won this event in 2008, to advance along with the pool winner, Karolina Pliskova, who won her first two matches but ended round-robin play with a 6-3, 6-1 defeat by Jelena Ostapenko earlier on Thursday.