MIAMI  -  Roger Federer knew he had things going his way at the Miami Open when he hit three shots off his frame during a wild 17-stroke exchange and still won the point because Filip Krajinovic dumped a half volley into the net.

Krajinovic quickly grabbed the ball and flipped it over the net as if continuing the rally, which drew cheers from the crowd and a smile from Federer. “We’re not robots,” Federer said. “I like when players show emotion like Filip did in that instant. It was a weird, strange, ridiculous point that I got very lucky to win somehow.”

A little lucky and really good, Federer won 7-5, 6-3 Monday to reach the fourth round. He improved to 14-2 this year, signaling he’s a threat to win his fourth Miami title. He’ll next play No 13 Daniil Medvedev, who won a battle of dominating serves against 6-foot-11 qualifier Reilly Opelka, 7-6 (5), 6-7 (5), 7-6 (0).

Among those departing in the women’s fourth round were Venus Williams and Indian Wells champion Bianca Andreescu. Williams lost to No. 2-seeded Simona Halep 6-3, 6-3, and Andreescu retired with a right shoulder injury while trailing Anett Kontaveit 6-1, 2-0. Andreescu, who is tied for the WTA lead with 20 match victories this year, said she felt pain and tightness in the shoulder. “I’ve played so many matches,” the 18-year-old Canadian said. “I guess it’s just my body’s way of telling me it has had enough. The doctor said it’s nothing too serious, but the pain is there.”

Andreescu said she will skip the tournament next week in Charleston, South Carolina, but plans to play the Fed Cup on April 20-21.

Andreescu defeated Kerber in the Indian Wells final on March 17 for her first career title. The injury ended Andreescu’s bid to become the fourth woman to win Indian Wells and Miami back to back. Halep and Kontaveit were joined in the quarterfinals by Petra Kvitova, who faced only one break point and beat Caroline Garcia 6-3, 6-3. Kvitova, a two-time Wimbledon champion, is ranked a career-high No 2 and will rise to No 1 if she wins the title. No 1 Naomi Osaka lost in the third round. Kvitova’s match was interrupted by rain for more than 90 minutes.