Serena Williams beat Romania's Simona Halep to win the season-ending WTA Tour Finals for the third year in a row on the event's debut in Singapore.
The American top seed won 6-3 6-0 to claim the WTA title for the fifth time.
Williams also gained revenge for suffering her heaviest defeat in 16 years against Halep in the group stage.
The 33-year-old, who won her 18th Grand Slam singles title at the US Open in September, will end the year as world number one for the fourth time.
"I had to play more Serena-style tennis and just do what I do best," said Williams.
"I was expecting a much better player than I was in the earlier round. Being ready for that really was able to help me out."
Halep could have eliminated Williams in the group stage had she lost to Ana Ivanovic in straight sets, but the Romanian lost in three to throw the champion a lifeline.
"I have no regrets, because I did my job on court against Ivanovic," said Halep. "I tried to win the match. I couldn't, but I never thought that I have to lose in two sets against Ivanovic."
Both Williams and Halep were below their best in the final, which failed to live up to the American's thrilling semi-final win over Caroline Wozniacki, but once she had clinched the first set there was little danger of Williams giving up her title.
She began the match in edgy fashion, having to save break point in her opening service game before being broken in her second, but Halep could not convert a chance to move 3-1 ahead and was pegged back.