Published: Jul 19, 2012 7:23 PM EDT
Updated: Jul 20, 2012 6:31 AM EDT

CARLSBAD, Calif. (AP) - U.S. Olympian Christina McHale held off Misaki Doi of Japan 4-6, 6-4, 6-4 at the Mercury Insurance Open on Thursday, advancing to a quarterfinal against No. 1 seed Marion Bartoli of France.

McHale, the No. 5 seed, needed three match points in the last game before she closed out the second-round match when Doi hit a backhand into the net.

McHale faced 19 break points, but Doi only converted three.

In another second-round match, Ursula Radwanska of Poland cruised to a 6-2, 6-1 win over lucky loser Melanie Oudin.

Radwanska, the younger sister of world No. 2 ranked Agnieszka Radwanska, served well and took advantage of the American's subpar serve to control the match.