Spaniard Rafael Nadal in his 56th title on clay of Rome made the best of a rain delay to come from behind in the deciding set and hit defending champion Alexander Zverev 6-1 1-6 6-3 in the Italian Open final on Sunday.

In his 56 titles - eight of them in Rome - he will reclaim the world number one ranking from Roger Federer when the revised ATP standings are released on Monday.

In spite of breaking to love in the first game, Nadal made an unsteady start, missing his serve in the opening game ahead of bouncing back.

The 31-year-old top seed bust Alexander Zverev to level the score and then turned up the heat, striking eight winners and making only four effortless errors to his opponent's 10 to seize the opener.

The 21-year-old Zverev regrouped, holding for the first time in the match at the start of the second set before breaking Nadal to lead 2-0.

They came into the final as the form player on the ATP Tour, and he got his rhythm that had Nadal on the back foot on his favorite surface. He carried his impetus into the third set, breaking Nadal to go 2-0 up and put on an early advantage.

Nadal kept himself alive in two more service games went by before play was stop its progress for the first time with the rain spitting down.