Serena Williams celebrates defeating Carla Suarez Navarro of Spain at the US Open tennis championships in New York, Sept 3, 2013. [Photo/Agencies]

At 31, Williams is campaigning to become the oldest US Open women's winner since tennis turned professional in 1968.

She has lost just 13 games from her five matches so far and said she has been balancing fun with work at Flushing Meadows.

"I'm having a blast this week," said Serena, who is also still alive in women's doubles with older sister Venus.

"I have just really been enjoying my matches. For me, I have to stay in that moment of fun, but intensity, but calm. If I can try to do those three things, it works out."

Suarez Navarro's consolation was a $325,000 check for being eliminated from her first US Open quarterfinal.

"I just want to go there and enjoy, but Serena was playing really, really good. I do everything I can," she said.

The Spaniard, who had ousted eighth-seeded Angelique Kerber of Germany in the fourth round, said the blustery conditions had made her task even more difficult.

"Serena is a strong player. When I play with the wind against me, I have no chance," said Suarez Navarro, who had hoped to rebound after the lightning-quick, 19-minute first set.

"I was thinking the situation can change, another set is a new set. But obviously, no."