Spain's attack is still struggling to turn dominating performances into goals, a worrying trend for the World Cup champions as they head to Brazil to defend their title.

Spain needed a pair of second-half goals from David Villa to get past El Salvador 2-0 Saturday in its final friendly match before the World Cup, a scoreline that didn't quite reflect just how Spain dominated its 68th-ranked opponent.

The world champions were barely troubled by El Salvador but still couldn't find more goals despite having striker Diego Costa available.

That could spell trouble for Spain, which is in a tough Group B where goal difference or goals scored could prove crucial in reaching the elimination stages.

Coach Vicente del Bosque says "we lack consistency and precision inside the area."