Simona Halep stayed on track for a third successive title at the Madrid Open by sweeping past in-form Elise Mertens in the second round.

Belgian Mertens, an Australian Open semi-finalist in January, went into the clash on a 13-match winning streak but has been battling illness and needed eight games just to get on the board before going down 6-0 6-3.

Halep, whose world No.1 ranking is also on the line, has dropped just four games in two matches at the Caja Magica and next faces Czech Kristyna Pliskova.

“I knew she’s coming with a lot of confidence. I had to start very strong and aggressive, which I did,” Halep said.

“After I played a few games, I felt really good on court. I felt very confident that I can win that match.”

Prague champion Petra Kvitova continued her winning streak on clay with a 6-3 7-6 (10/8) victory over Olympic champion Monica Puig.

It was a mixed serving day for Kvitova, who hit nine aces and the same number of double faults.