Miami Open: Federer overcomes sluggish start to beat Krajinovic 7-6, 6-7, 7-6

Roger Federer overcame a sluggish start to defeat Filip Krajinovic 7-5 6-3 and Kevin Anderson's booming serve proved too much for Joao Sousa as the big names advanced to the fourth round of the Miami Open on Monday.

Serb Krajinovic broke Federer to jump to an early 2-1 lead and it looked like an upset could be in the works against the 20-times Grand Slam champion.

But fourth seed Federer broke back the next game and seized the momentum when he blasted a cross-court forehand winner to break Krajinovic again and take the closely fought first set.

The 37-year-old Swiss coasted after that, thanks to an overpowering serve that Krajinovic struggled to read.

Federer said he was able to shrug off his loss to Dominic Thiem in the BNP Paribas Open final at Indian Wells last week because of his years of experience.

"Nowadays I am able to flush it out quickly. I was the worst at it when I was a teenager... right after it was all over I would cry and be so sad and disappointed," he said.

"I wasn't an angry person really, it just broke my heart.

"Nowadays I feel like 'look, I gave it all I had'. Thiem came up with the goods, I maybe didn't. That's it, it's over."

Next up for Federer is a clash with Russian Daniil Medvedev after the 13th seed defeated American qualifier Reilly Opelka in a 7-6(5) 6-7(5) 7-6(0) slugfest that included 41 total aces.

Anderson mixed 13 aces of his own with just one double-fault to seal a 6-4 7-6(6) victory over Portuguese Sousa earlier on Monday.

The towering South African sixth seed will be a heavy favourite on Tuesday when he faces unseeded Australian Jordan Thompson, who beat Grigor Dimitrov 7-5 7-5.