Indian Wells (California): Switzerland's Stan Wawrinka defeated Germany's Philipp Kohlschreiber 7-5, 6-3 to advance to the round of 16 at the BNP Paribas Open here.

Wawrinka will now take on Yoshihito Nishioka of Japan, who upset the Czech Republic's Tomas Berdych 1-6, 7-6 (7-5), 6-4, reports Efe.

"It was a really good match. I'm very happy ... I was serving well. I think I'm moving better and better, and it's all positive so far," Wawrinka said on Monday.

"I know how he's playing - more from the baseline, using his power. It's going to be interesting. I never practice with him, so it's going to be the first time we're going to be against each other. So I'm sure it's going to be a good match," he added.

In other men's action, Austria's Dominic Thiem defeated Germany's Misha Zverev 6-1, 6-4, while France's Gael Monfils took out American John Isner 6-2, 6-4.

In women's category, American Madison Keys rolled over Japan's Naomi Osaka 6-1, 6-4 in 57 minutes.

"I'm just happy to be out here, happy to have another win, happy to get to play tomorrow," Keys, who was sidelined with an injury for two months, said.

Keys's opponent in the round of 16 will be Denmark's Caroline Wozniacki, who rolled over the Czech Republic's Katerina Siniakova 6-3, 6-1.

"I definitely had really low expectations (before the tournament). I was, like, if I get a set, I'll be happy. And to win? It's always tough to come back and everyone is in the middle of their season," Keys said.

In other women's singles action, Germany's Angelique Kerber eked out a 7-5, 3-6, 7-5 win over France's Pauline Parmentier, while American Venus Williams, the No. 12 seed, beat the Czech Republic's Lucie Safarova 6-4, 6-2.