The match started slowly as both sides looked to ease themselves into the game, a theme that continued throughout the first half as they struggled to create clear cut chances.
Things went from bad to worse for the visitors minutes later when Coutinho was shown a second yellow card to give Espanyol a mountain to climb.
Osasuna extended their lead 15 minutes later, and it was Raul Garcia who struck once again, netting his and his side's second of the match.
A miserable day for Espanyol was capped off five minutes from time when they had another man sent off, this time Juan Daniel Forlín seeing a second yellow before receiving his marching orders.
The result doesn't change either team's position in the Primera Division table, with Espanyol remaining ninth, now four points behind sixth-placed Osasuna.