Villa played his first competitive minutes since breaking his leg last December and capped the win with a goal.
Barcelona: Barcelona thrashed Real Sociedad 5-1 with Lionel Messi scoring twice, striking first Sunday in the likely two-way fight for the Spanish league title after Real Madrid had drawn 1-1 against Valencia.
To sweeten the debut of Barcelona coach Tito Vilanova, David Villa played his first competitive minutes since breaking his leg last December and capped the win with a goal.
The Spain striker came on in the 75th minute to a standing ovation at Camp Nou — and nine minutes later he scored.
It was Villa's first competitive match after breaking his shin bone in last year's Club World Cup.
Villa, who missed the European Championship, played limited minutes in preseason matches for Barcelona.
Teammate Xavi Hernandez said the big win was not as welcome as having Villa back.
"The best news is that Villa has returned, and he did so with a goal," said Xavi. "The win is great, but Villa's return is the most important thing."
After scoring, Villa lifted his jersey to reveal a T-shirt with the message: "Impossible without all of you."
While Cristiano Ronaldo was lackluster when Madrid opened its title defense, Messi picked up right where he left off after scoring a league-record 50 goals last season.
With the score level at 1-1 early on, the three-time Ballon d'Or winner scored two quick goals to decide the match at the Camp Nou.