La Liga top scorer Soldado, in the running for a place in Spain's Euro 2012 squad, tapped in at the back post after home keeper Juan Pablo could only parry a shot in the 30th minute.
Valencia, held to a disappointing 0-0 draw at Genk in the Champions League in midweek, maintained their 100 percent league record with nine points.
Malaga were 1-0 winners at Real Mallorca where a Martin Demichelis header was deflected into his own net by Mallorca's Pablo Caceres just before the break.
Nigeria striker Iku Uche scored Granada's first goal in the Spanish top flight in 35 years earning the promoted side a surprise 1-0 home win over Villarreal.
The Andalucians had lost their first two matches without scoring, and Uche's powerful 55th minute header proved to be decisive as Giuseppe Rossi missed a late penalty for the visitors.
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