Athletic are fourth on 59 points in Spain's final Champions League spot, six more than Sevilla who thumped Espanyol 4-1 over the weekend, and nine ahead of sixth-placed Real Sociedad, beaten 4-0 at home by Real Madrid on Saturday.
The Basque side responded well to their defeat by Atletico Madrid in their last match, starting the game at a high tempo and cutting the Levante defence open in the early stages.
A sloppy challenge from Juanfran on Iker Muniain earned Athletic a penalty which Mikel San Jose sent wide but the visitors were soon ahead anyway.
A shot from Aduriz from the edge of the area deflected off Levante defender Simao Mate, wrong-footing Keylor Navas, and went into the corner.
It was a lacklustre display from mid-table Levante and on the point of halftime Aduriz netted his 13th goal of the season as he headed home an Ander Herrera cross.
After the restart Levante had more impetus but could only pull one goal back with a Ruben Garcia cross hitting San Jose and looping over keeper Gorka Iraizoz and into the net.
"At the end they were pushing forward and we were sitting back more," Athletic coach Ernesto Valverde said.
"Having gone ahead we were going close but not scoring and then they got one back which made it difficult for us. From now on it will be a fight until the final game and we are up against strong rivals (for a Champions League place) like Sevilla and Real (Sociedad).
The three-way battle at the top of La Liga remains fierce with Real three points adrift of leaders Atletico Madrid, who beat Villarreal 1-0 at home on Saturday and have 79 points.
Barcelona are on 78 points following their 3-1 victory over bottom side Real Betis.
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