Roger Federer's impressive start to the 2017 campaign continued as he beat Spain's Roberto Bautista Agut 7-6 7-6 in the fourth round of the Miami Open.

The Australia Open champion has lost only one match this year after returning from a five-month lay-off, and claimed the tie breaks 7-5 and 7-4 to progress to the quarter-finals in Florida.

Czech Tomas Berdych awaits the Swiss in the last eight after he beat France's Adrian Mannarino 6-3 7-5.

However, the news was not as good for Federer's compatriot and top seed Stan Wawrinka, who suffered a surprise defeat to German teenager Alexander Zverev.

Wawrinka took the first set 6-4 but Zverev converted four of his five break points as he won the next two 6-2 6-1.

Zverov will play Nick Kyrgios in the quarter-finals after the Australia overcame David Goffin of Belgium 7-6 6-3.

Second seed Kei Nishikori was a 6-3 4-6 6-3 winner against Federico Delbonis, with the Japanese player facing Fabio Fognini next after the Italian thrashed Donald Young 6-0 6-4.