Finals Day at the TEB BNP Paribas WTA Championships kicked off with a star-studded doubles final.
All four players in the doubles final are Top 10 in doubles, and are or have been Top 25 in singles.
It was Hsieh Su-Wei and Peng Shuai who won, beating Ekaterina Makarova and Elena Vesnina, 64 75.
The singles final followed the doubles, pitting World No.1 Serena Williams against World No.5 Li Na.
Williams had won her last 14 matches at the season finale, the second-longest streak ever at the event.
And despite a slow start - she was three games away from losing at 26 33 - she never gave up...
Williams tightened the screws and found her range, winning nine games in a row to prevail, 26 63 60.
Williams dropped after blasting her 30th winner of the match on match point - a huge backhand winner.
The trophy presentation took place after both finals, combining the singles and doubles stars.
Makarova and Vesnina had a stellar week - they beat co-World No.1s Sara Errani and Roberta Vinci.
But it was Hsieh and Peng who got the last word in, improving to 9-0 together in WTA doubles finals.
Williams has always struggled with Li but almost always comes through - she's 10-1 against her now.
Williams has now won 32 of her last 34 matches against Top 5 players, the losses to Victoria Azarenka.
Turkish Tennis Federation President Osman Tural - and all the Turkish fans - lifted everyone too.
Williams wraps up a phenomenal season - 78 match wins, 11 WTA titles, two Slams and year-end honors.