NEW YORK (Reuters) - Swiss Olympic champion Belinda Bencic survived a punishing first-set tiebreak to defeat seventh seed Iga Swiatek of Poland 7-6(12) 6-3 in the fourth round of the U.S Open on Monday.

The pair battled through the 23-minute tiebreak under hot and sunny conditions inside Louis Armstrong Stadium as Swiatek saw her 5-2 lead in the breaker evaporate when Bencic won four straight points, with each player making unforced errors.