Rafael Nadal survived a stunning fightback from Alexander Zverev to win a record eighth Italian Open.
Nadal cruised to the first set before defending champion Zverev won nine of the next 11 games to take the second set 6-1 and lead 3-1 in the decider.
But the Spaniard turned the match around following a lengthy rain delay and closed out a 6-1 1-6 6-3 victory.
The win will see Nadal regain the world number one ranking before the French Open which starts next Sunday.
Roger Federer had regained top spot in the rankings when Nadal lost to Dominic Thiem at the Madrid Masters last week, his only defeat on clay this season.
Nadal has now won three clay-court titles from four tournaments in the lead-up to his bid for an 11th Roland Garros title in Paris.
Nadal cruised to the first set in just 32 minutes and had looked on course for a routine victory against in-form Zverev, who had won 14 matches in a row and 30 matches in total this season – more than any other player.
But the 31-year-old made a number of uncharacteristic errors in the second set while world number three Zverev upped his game to level at 1-1.
The German, 21, broke Nadal’s serve in the opening game of the deciding set and maintained that break to lead 3-1 going into an 11-minute rain delay.
Nadal won the game after the players returned only for play to be halted by a second, longer rain delay, after which he won four games in a row to clinch the match.
The win is Nadal’s 78th ATP Tour title and takes him clear of John McEnroe into fourth place in the list of most men’s titles won in the Open era.
It also extends Nadal’s impressive record in Rome where he has won the title more than any other player with Serbia’s Novak Djokovic second on four titles.
|Most titles in the Open era|
Russell Fuller, BBC tennis correspondent
Zverev was just three games away from a first win over Nadal – and a hugely significant one, on clay, so close to the French Open – when rain dragged the players off court.
Nadal barely put a foot wrong on the resumption, winning five games in a row to make sure he will be the world number one as well as the top seed at Roland Garros.
But make no mistake, Nadal was seriously rattled by the way Zverev played – the German won nine games out of 11 from the start of the second set.
Nadal adopted his customary deep returning position, and at times was dominated by the German’s big serve and crisp, flat, ball striking.
They will be the top two seeds at Roland Garros, and may well meet in the final in Paris.
First, though, Zverev must survive the first four rounds, something he is yet to achieve at any Grand Slam.