Caroline Wozniacki has been sent tumbling out of the Rogers Cup after blowing a one-set lead against Sorana Cirstea.

The Romanian, ranked 27th in the world, hung tough after losing a first set rife with breaks of serve by seven games to five.

Both players broke twice in the second set, which went to a tie-break. However, Cirstea, sensing that she could be heading for the exit, whitewashed the Dane 7-0 in the second-set decider.

That took the wind out of the sails of Wozniacki, who eventually succumbed to a 7-5 6-7 4-6 defeat after just under three hours on the Grandstand court.

Cirstea will play either Jelena Jankovic or Sharon Fichman in the next round.