Atletico were missing top scorer Diego Costa and playmaker Arda Turan through injury but dispatched Villarreal with an efficient, if unspectacular, performance in front of their boisterous fans enjoying the club's best campaign since they last won Spain's domestic league in 1996.
Garcia nodded in a Koke corner in the 14th minute at a packed Calderon and the homeside comfortably soaked up sustained Villarreal pressure in the second half to move on to 79 points from 32 of 38 matches, three more than their tally from last season when they finished third.
They are four ahead of second-placed champions Barcelona, who host bottom side Real Betis later on Saturday. Real Madrid are two points behind Barca in third ahead of their game at sixth-placed Real Sociedad.
Atletico's Argentine coach Diego Simeone has transformed the team into genuine contenders in Spain and Europe since taking over at the end of 2011 despite the club having about a fifth of the resources of wealthier rivals Barca and Real, the world's richest clubs by income.
Atletico and Barca are locked at 1-1 in their Champions League quarter-final after Tuesday's first leg at the Nou Camp and play the return in Madrid on Wednesday.
They also meet in Barcelona in La Liga on the final day of the season.
Elsewhere, Rayo Vallecano coasted past Celta de Vigo 3-0.
- Sports & Recreation
- Diego Costa
- Arda Turan