Defending champion Rafael Nadal began his Italian Open campaign with an emphatic 6-3 6-1 victory over big-serving American John Isner to move into the last-16.

Nadal, who returned from a rib injury this month and fell at the quarter-final hurdle in Madrid last week, dominated Isner who struggled to find answers.

The second set was no contest as Nadal broke in the opening game to set the tone and he did not look back as Isner ran out of gas.

Nadal will play Denis Shapovalov in the next round, against whom he saved two match points in the third round last year en route to his 10th title.