MADRID (AP) — Top-ranked Serena Williams won her opening match on the red clay of the Madrid Open on Sunday.

She and other stars are glad the tournament returned to the traditional surface after its trial with blue “Smurf” clay flopped last year.

After dispatching Yulia Putintseva of Kazakhstan 7-6 (5), 6-1, the defending champion said she liked the new courts at the Caja Magica.

“I think these clay courts are really good,” she said. “I think they’re a little bit faster than the ones I was practicing on in Paris. For me, that’s always a good sign.”

Rafael Nadal and Novak Djokovic were even more enthusiastic about the removal of the blue clay, which both players had heavily criticized for being slippery after early exits last year.

“I think that obviously the court last year was not up to the level that we needed,” Nadal said. “It was not prepared to be a competitive court.

“But the courts are impressive this year. In Madrid, we have the problem of the dry climate, so it’s very difficult to have the clay that settles down properly, a clay that’s the same as in other places. I think this year we have managed to have good clay here.”

Djokovic called the traditional red clay “great,” adding that everything he had heard from other competitors was “positive.” The world’s top-ranked player had threatened to not come back unless the blue clay was discarded.

Roger Federer won here last year despite the challenge the slick courts posed. The Swiss star was nevertheless pleased with the decision to go back to a standard playing surface, saying that the new courts were the best he had seen at the event.

“I don’t know if that was due to the color, but this tournament has, in the past, had issues with the quality of the court,” Federer said. “I think through what happened last year, you know, the controversy around the blue clay, I think it was a big eye-opener to have a proper court here now.”

Nadal, Djokovic and Federer have first-round byes.

Williams had her serve broken early to fall behind Putintseva 3-1 in the first set. But Williams soon settled down after breaking back. Once she got through the tiebreaker, she dominated the second set.

“I felt a little sluggish out there, but I’m happy I was able to win the match,” Williams said. “Honestly, I obviously have to and want to play better as each match goes on.”

She next faces Lourdes Dominguez-Lino of Spain.

Older sister Venus Williams withdrew early Sunday morning before her first-round match because of back problems.

Eighteen-year-old American Madison Keys upset fifth-ranked Li Na of China 6-3, 6-2. Keys, ranked 63rd, had five aces and converted 5 of 7 break chances to eliminate the 2011 French Open winner.

Former top-ranked player Caroline Wozniacki was ousted by Yaroslava Shvedova of Kazakhstan 6-3, 6-4. Shvedova overcame nine double-faults by converting 5 of 15 break chances to beat the 10th-seeded Wozniacki.

Fourth-seeded Agnieszka Radwanska of Poland defeated Tsvetana Pironkova of Bulgaria 6-2, 6-4 and will play Britain’s Laura Robson.

Other seeded winners included Angelique Kerber, Petra Kvitova, Marion Bartoli, Dominika Cibulkova, Ana Ivanovic, Nadia Petrova and Maria Kirilenko.

In the men’s event, Gilles Simon, Fernando Verdasco and Jeremy Chardy all won matches to move on to the second round.