Nick Kyrgios holds nerve to stun Roger Federer

Australia's Nick Kyrgios continued to demonstrate his potential by beating Madrid Open top seed Roger Federer in a three-set tussle on Wednesday.

Fresh from a run to the Estoril Open final, Kyrgios was edged out of a narrow first set, but recovered to progress 6-7 (1-7) 7-6 (7-5) 7-6 (14-12).

Federer was bidding for a fourth Madrid crown, but became the 20-year-old's second top-10 career scalp.

In a match that saw 38 aces, Kyrgios held his nerve and saved two match points in a lengthy third-set tie-break to book a third-round clash with John Isner.

Earlier, Rafael Nadal made a winning start to his Madrid Open title defence with a 6-4 6-3 victory over Steve Johnson.

Nadal - dumped out in the last 16 at the Barcelona Open last month - held serve throughout and hit 14 winners in his first career meeting with the American to extend his winning streak in Madrid to 11 matches.

Sixth seed Tomas Berdych also negotiated his first test of the tournament, coming through in straight sets against Richard Gasquet.

The Frenchman was often undone by Berdych's serve, as the world number seven hit 10 aces in a 7-6 (7-3) 7-5 victory, while seventh seed David Ferrer made light work of fellow Spaniard Albert Ramos-Vinolas with a 6-4 6-0 victory.

Ferrer was rarely troubled as he maintained his 100 per cent record against the 27-year-old qualifier to ensure a meeting with another home favourite Fernando Verdasco " a surprise winner against ninth seed Marin Cilic.

Grigor Dimitrov did things the hard way in booking his last-16 place, having fallen behind early in his win over Fabio Fognini, with Feliciano Lopez downed in straight sets by Leonardo Mayer.

The 10th seed finished strongly to claim a 3-6 6-2 7-5 victory, while there were also victories for Jo-Wilfried Tsonga, Roberto Bautista-Agut and Isner.