Nadal went down to defeat in Sunday's Monte Carlo final to Novak Djokovic 6-2, 7-6 (7/1) but is not mourning the end of a 46-match winning run at the prestige venue.
"With not much preparation, I was able to play in the finals, a few matches," said the knee injury victim who missed seven months but who has since played in five straight finals and won three trophies.
"This week is going to help me be fit for the next weeks."
Nadal is the king of the home clay in Catalonia.
The 26-year-old has won seven of the past eight editions at the venerable Real Club de Tenis. His only miss came in 2010, when he did not play, compatriot Fernando Verdasco keeping the trophy firmly in Iberian hands.
Nadal began his clay season last week and showed his usual superb form on his surface of choice - just not enough to get past an inspired Djokovic - though Nadal can see improvement.
"I feel for moments in the second set I played my best tennis of the week. So that's an important thing."
But there is a shift in the ground at this edition, with the fifth-ranked Nadal seeded second behind countryman David Ferrer, who takes the top spot in the draw.
Ferrer is playing after missing the Monte Carlo Masters with a thigh injury which bothered him in his losing Miami final to Andy Murray last month.
The hard-working Ferrer has a grudge to settle with his celebrated Davis Cup teammate, who has beaten him in four of the last five Barcelona finals, including the last two.
All 16 seeds get byes into the second round, which will leaving opening play to outsiders including Australian Bernard Tomic, Czech veteran Radek Stepanek and Spain's Tommy Robredo, who got his career back on track with the Casablanca title this month.
Czech Tomas Berdych takes the third seeding at the event he last played in 2009, while Spain's Nicolas Almagro is seeded fourth ahead of Canadian Milos Raonic.
Japan's sixth seed Kei Nishikori, a quarter-finalist last year, makes his season clay start, with Argentine Juan Monaco seeded seventh and German Philipp Kohlschreiber eighth.