STANFORD (AP) — Serena Williams stared at the court, took a deep breath and seemed to clear her head after falling behind in the first set. She dominated the rest of the way.

Playing her first tournament since her departure from Wimbledon because of equilibrium problems, the top-ranked Williams won her WTA-leading fourth title of the year, beating third-seeded Angelique Kerber 7-6(1), 6-3 on Sunday in Bank of the West Classic.

Kerber, 0-4 in finals this season, won five straight games to go up 5-1 and was serving for the first set at 5-2. Williams saved two set points and went to win five games in a row.

“I blinked my eye and I was down 1-5,” Williams said. “Angelique was playing well and I thought ‘What’s going on?’ I tried to relax, not think about anything and just do the right thing.”

The eighth-ranked Kerber forced a tiebreaker, but Williams took the first five points.

“It’s a good thing that it happened,” Williams said. “When I’m not playing great I know I can make some kind of comeback.”

Williams didn’t play well in any of the first sets this week but always found a way to win.

“I’ve been training hard all year and hopefully that pays off, especially after Wimbledon,” Williams said. “I stayed positive here. This shows I’m moving in the right direction.”

Questions were raised after she retired from a doubles match with sister Venus at Wimbledon in June. A viral infection affected her equilibrium.

She answered those questions with an exclamation point Sunday.

“Every week is a new week and all I can do is try and improve,” Williams said. “For me it’s all mental: being there, being positive and being good to myself.”