Serena Williams was left disappointed with her performance against Victoria Azarenka in the US Open third round, despite winning in straight sets.
The number 28 seed demolished the Russian 6-1 in the first, before taking the second 7-5 on a tie-break.
"I think I played really well [in the first set]," said the 29-year-old. "I probably should have kept doing those things. If I was in a zone, it didn't last long.
"I definitely wasn't happy with the way I played today. I was a wee bit disappointed."
The three-time US Open winner takes on Ana Ivanovic or Sloane Stephens in the next round.
