Djokovic has found form on the red dirt this week, reaching a first ATP Tour semi-final of 2018, but Nadal, who lost his top-ranked status after surprisingly exiting the Madrid open in the last eight to Dominic Thiem, was a step too far.

The long-time on-court rivals contributed to an encounter high in quality in the Rome sun, Nadal requiring a tie-break to nudge in front before enjoying a slightly more straight-forward second set.

After seven consecutive defeats to Djokovic — all in straight sets — Nadal has now beaten the Serbian in their past two contests and he remains in fine fettle ahead of his French Open defence.

For now, though, Nadal's focus will be on an eighth title in the Italian capital, and first since 2013, that would see him head back to the top of the rankings.

Djokovic had been granted significantly less recovery time than his opponent after Saturday's (AEST) quarter-finals, but he initially showed no ill effects, going toe-to-toe with Nadal and almost breaking ahead immediately.

The No.1 seed found his feet and broke in front in the sixth game, winning the second of two high-class rallies.

But the pair was level again when Djokovic enjoyed the rub of the green with a shot that clipped the net in game nine, and the scores stayed level to set up a breathless tie-break in which the two greats traded blows.

Nadal's energy and consistency shone through to take the first set, visibly irking a frustrated Djokovic, who appeared to feel the heat in the second and conceded an early break to love.

Although Djokovic recovered some momentum and pushed Nadal all the way, including a 10-minute eighth game, he could not overturn the deficit and was broken again when serving to stay in the match at 5-3 down.

World No.2 Nadal will now face either Marin Cilic or the in-form Alexander Zverev — champion in Madrid and victor in Rome 12 months ago — in Monday's (AEST) final.