French Open 2016: Serena Williams struggles past Mladenovic to enter the fourth round

Holder Serena Williams survived her toughest challenge yet at this year's French Open as she battled into the fourth round with a 6-4 7-6(10) win over Frenchwoman Kristina Mladenovic in a rain-disrupted match on Saturday.

The American's victory charge was halted for more than 2-1/2 hours as a thunderous downpour descended over Roland Garros with Williams leading 6-4 6-6.

When the duo came back on court to resume battle in a titanic tiebreak lasting 17 minutes, Williams produced some howlers as four match points went begging.

At 6-5 she drew a chorus of 15,000 gasps as she smashed the ball metres over the baseline and Williams was way off target at 8-7 too, misfiring a forehand well beyond the court markings. The American then drew on the wealth of experience that has earned her 21 grand slam titles to save a set point before sealing victory when Mladenovic belted a forehand wide.

She will next face Ukrainian 18th seed Elina Svitolina, who knocked out 2008 champion Ana Ivanovic.