Nadal beat fellow Spaniard Pablo Carreno Busta 6-3 6-2 to stand on the brink of being crowned champion for a 12th time at the Real Club de Tenis Barcelona 1899.
The No.1 seed won 77 per cent of points on his first serve and returned superbly in yet another sublime clay-court exhibition.
Nadal broke Carreno Busta in his compatriot's first service game and ominously charged into a 5-1 lead in imperious fashion on Pista Rafael Nadal.
Carreno Busta broke back to prolong the opening set, but the 20-time grand slam champion wrapped it up in 45 minutes before swiftly taking charge of the second.
The world No.3 breezed into a 4-0 advantage and did not face a solitary break point as he took just shy of an hour and a half to set up a showdown with Tsitsipas, who knocked him out of the Australian Open at the quarter-final stage in February.
Tsitsipas maintained his magnificent form with a 6-3 6-3 defeat of Jannik Sinner.
The in-form Greek won the Monte Carlo Masters last weekend and matched Andrey Rublev's ATP tour-leading total of 26 victories this season by steering past Sinner.
No.3 seed Tsitsipas has won all 17 sets he has played on clay this season, having saved all four break points that Sinner earned.