Nadal eased to his fifth title in just seven tournaments since returning from a seven-month injury layoff due to tendinitis in his left knee as he beat Stanislas Wawrinka 6-2, 6-4 in little over an hour to claim his third title in the Spanish capital.
He now has 55 career titles with 40 coming on clay, an astonishing record that prompted Wawrinka to describe the Spaniard as a "killer" on clay courts.
His win on Sunday was also a 23rd Masters Series title.
"It's true these last matches I have been able to reach that goal, that line, that place where I want to be playing, the kind of play that I'm aiming for," he said.
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"Since we started playing on clay in Europe, these last two matches are the best I have played. I've realised that my forehand is working again at its highest level and I'm able to open the angles and play a lot of winners.
However, the world number five still refused to accept that he is the clear favourite for Roland Garros, which starts in two weeks, and insisted his mind is solely set on retaining his title in Rome this week.