Susaeta cracked home a superb first-time shot five minutes before halftime at the San Mames to put Bilbao nine points clear of fifth-placed Real Sociedad ahead of their Basque rivals' match at Almeria on Monday.
Getafe, winless in 14 La Liga outings stretching back to mid December, are just above the drop zone in 17th on 28 points.
Espanyol and Levante, who are in with a chance of a place in the Europa League, drew 0-0 at Espanyol's Cornella El Prat stadium in Barcelona, while Granada pulled further away from danger with a 1-0 win at home to Elche.
Rayo Vallecano, who appeared doomed to relegation a few weeks ago, drew 1-1 at fellow strugglers Real Valladolid and have now taken 10 points from their last four games.
In Sunday's games, leaders Real Madrid can deal a severe blow to Barcelona's chances of a fifth title in six years with a win at home to their arch rivals in the 'Clasico'.
Real are top on 70 points, three ahead of city neighbours Atletico Madrid, who play at bottom side Real Betis. Barca are a point behind Atletico in third, 11 points ahead of Bilbao.
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