Andy Murray is into his first final of the season-ending ATP World Tour Finals and on course to end the year as world number one after beating Milos Raonic in a gripping semi-final.
Murray won 5-7 7-6 (7-5) 7-6 (11-9) in three hours and 38 minutes.
Murray must match Novak Djokovic’s results at the O2 Arena to stay ahead of the Serb in the rankings.
Djokovic plays Japanese fifth seed Kei Nishikori in the second semi-final at 20:00 GMT.
The victory over Raonic extended Murray’s winning streak to a career-best 23 matches, stretching back to September.
It was the Scot’s second lengthy encounter in three days, following what was a tournament-record three hours and 20 minutes required to beat Nishikori in the round-robin stage on Wednesday.