The victory lifts Espanyol to 21 points, 3 behind cross-town rivals FC Barcelona after 11 matches. Athletic, with 10 points, are 17th, reports Efe news.
Neither side started very brightly on a rainy night in front of some 14,000 spectators at the RCDE Stadium and 30 minutes passed before the first shot on Monday night.
The breakthrough came in the 42nd minute, when Iglesias got his head to a cross from Didac Vila for his sixth goal of the season.
Athletic were quick to react. On the ensuing sequence, Iñaki Williams left three Espanyol players in his wake before unleashing a strike that bounced off the post, while Raul Garcia tested home goalkeeper Diego Lopez in the first half stoppage time.
Desperate to salvage a point, the Basque squad had no choice but to go forward in the second half, creating plenty of space for attack-minded Espanyol, who looked the more likely to score.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)