Federer through, Andreescu out in Miami

The Swiss superstar produced an excellent all-round performance despite being tested by the world number 103 who belied his lowly ranking by producing some excellent tennis during an exciting first set.

Federer, however, stylishly weathered the storm to seal the win - the 52nd of his career in Miami - to move into the quarter-finals and a match with either American Reilly Opelka or Daniil Medvedev.

"It was a difficult start, he's a great returner so I knew I had to up my percentages and I served really well," said Federer, who hit 14 aces and won an impressive 74% of points on his first serve.

"It was more humid today so I am just delighted to get through."

Krajinovic struggled badley with injury last year, problems with his ankle, left foot and hand restricting him to just seven tournaments in the first seven months of 2018.

Yet the Serb had looked impressive in his run to the third round, especially after dispatching Stan Wawrinka on the way to Monday's meeting with Federer.

Some fierce hitting from the back of the court surprised the predictably pro-Federer crowd at Hard Rock Stadium and a brilliant run and flick over the net handed helped set up an early break for 3-2.

Keeping the pressure on, however, was a different matter. 

Federer immediately broke back and although chances continued to present themselves to Krajinovic - he missed the opportunity to break the Swiss star’s serve at 5-5 - it was the 20 time Grand Slam winning champion who prevailed.

At 6-5, Federer went 15-40 up on the Serbian's service game and another backhand winner gave the 37-year-old the lead.

The second set wasn't as competitive, Federer easing 3-0 up as the wind was taken out of the Serb's sails. 

He lost the final game to love with the three time Miami Open winner easing home in style to finish with 36 winners compared to the 27 year-old's 18.

In the women's draw, Bianca Andreescu, the 18-year-old Canadian sensation who won the title in Indian Wells, was forced to withdraw in the second set of her fourth round match with Estonia’s Anett Kontaveit.

Andreescu was 1-6 0-2 down before a shoulder injury ruined her chances of another run to the finals.

Petra Kvitova, the world number 3, booked her place in the last eight, beating Caroline Garcia 6-3 6-3 in a match which was held up for one hour and 40 minutes because of rain in South Florida. 

Kvitova plays Australian Ashleigh Barty for a place in the semi-finals.