World No1 Serena Williams won the Miami WTA title for the seventh time with a 7-5, 6-1 win over China’s Li Na.

In a battle of the world’s top two players, the US superstar took her tally of WTA titles to 59. She added a second trophy in 2014 to the one she lifted in Brisbane in January.

The 32-year-old Williams, who first played at Miami as a 16-yearold, was strangely subdued as she seemed to sleepwalk through the first half hour of the match.

Trailing 4-2, she fought off three break points in the seventh game only to surrender her serve for a second time on a double fault.

Williams fought back by winning the next five games to take the set, saving a set point in the 10th game and hanging on to break Li in a 12th game that went to deuce six times.

The American delivered just three aces in a match that lasted just under two hours, and landed just 42 per cent of her first serves.

She seized a 5-1 lead in the second set with a fierce backhand winner on her fifth break point of the game and wrapped up the contest on her first match point.

Li, the reigning Australian Open champion, has now lost 10 straight matches against Williams. Her only victory in their 12 meetings was back in 2008.

On how much her seventh Miami success means to her, Williams said: “It was really important especially playing against Li Na. She started out so well and I just thought ‘oh my gosh I just need to hang in there’.

“Really at that moment (down a double break) I felt that I had nothing to lose and I was able to relax.”

Williams is the fourth woman in the Open era to win the same tournament seven times, joining Chris Evert, Steffi Graf and Martina Navratilova.