The revitalized Spaniard backed up his victory in the Monte Carlo Masters by claiming the Barcelona Open for a record ninth time, drawing him level with Argentina's Guillermo Vilas on 49 career clay-court titles.
Nadal beat two-time defending Barcelona champion Kei Nishikori 6-4 7-5 in a hotly-contested final in the Catalan capital.
It was his 10th straight victory of the European clay court season, which culminates with the second grand slam of the season in Paris next month.
Both men had reached the title match without dropping a set and something had to give.
Nishikori started brightly but a sloppy game saw him fall an early break behind at 3-1 in the first set.
The Japanese star fought back to level, but in the 10th game he was broken again to concede the opener.
Bidding for only his second win over Nadal in 10 matches, Nishikori achieved an early break in the second set only for his opponent to produce his best tennis of the week in winning the next four games.
Victory looked a formality until Nishikori dragged himself level again.
Nadal had his first match point at 5-4, but closed out the two-hour match two games later.
"In the second set I let a lot of opportunities go, but I am very happy to have resisted mentally and happy to win," he said.
The back-to-back tournament wins are a welcome boost for the 29-year-old Nadal, who started the season slowly and lost in the first round of the Australian Open.
But his ninth title in Monte Carlo, in his 100th ATP Tour final
, has clearly boosted his confidence ahead of Masters 1000 tournaments in Madrid and Rome before the ultimate clay-court test at Roland Garros for the 14-time grand slam winner.
On the WTA Tour, Angelique Kerber of Germany won her first tournament since her Australian Open triumph with victory in the Stuttgart final, 6-4, 6-0 over qualifier Laura Siegemund.
It was her second straight title at the prestigious clay court tournament, making light work of Siegemund, who had put out seeds Simona Halep, Roberta Vinci and Agnieszka Radwanska on the way to final.