Top seed Stan Wawrinka was stunned on his birthday at the Miami Open as Roger Federer and Rafael Nadal reached the quarter-finals.

Wawrinka, celebrating his 32nd birthday on Tuesday, suffered a fourth-round loss to talented German Alexander Zverev.

Federer and Nadal may have been below their best, but they still overcame Roberto Bautista Agut and Nicolas Mahut respectively.

Meanwhile, Kei Nishikori and Tomas Berdych also reached the last eight.

NO BIRTHDAY PARTY FOR STAN

Wawrinka, the top seed, was beaten for the second time in as many meetings with Zverev, the teenager claiming a 4-6 6-2 6-1 victory.

Zverev was in complete control in the third set, losing just 10 points and only one on serve in a dominant display.

Awaiting him in the quarter-finals is another talent in Nick Kyrgios after the Australian beat David Goffin 7-6 (7-5) 6-3.

FEDERER BATTLES THROUGH

Federer was well below his best but claimed a sixth consecutive straight-sets win over Bautista Agut with a 7-6 (7-5) 7-6 (7-4) triumph.

Two-time Miami champion Federer appeared in command early but dropped away before fighting his way past the Spaniard.

Next up for Federer is Tomas Berdych, the Czech 10th seed and 2010 runner-up having beaten Adrian Mannarino 6-3 7-5.

JOB DONE FOR NADAL

Nadal continued his run through with a 6-4 7-6 (7-4) success over Mahut.

The fifth-seeded Spaniard and four-time runner-up only managed to break the Mahut serve once, but he did not face a break point in a relatively comfortable win.

He faces a bigger test in the last eight in Jack Sock, whose fine form continued with a 6-2 6-1 thrashing of qualifier Jared Donaldson.

The other quarter-final will be between last year's runner-up Nishikori and Fabio Fognini.

Nishikori overcame Federico Delbonis 6-3 4-6 6-3, while Fognini brushed past Donald Young 6-0 6-4.