Ronald Araujo's scissor-kick had Barcelona eyeing victory, only for Maxi Gomez to pounce with an equaliser to thwart the under-pressure hosts.

"First of all it was a difficult game, it was difficult at 1-0 down," Koeman told Barcelona's official club website.

"You score twice, you're the winning team in the second half and you need to be a little bit more concentrated to see what will happen.

"We controlled the game, we had good opportunities to score the third, but then you have to understand maybe 2-1 is the maximum.

"One or two moments in the defensive way, not to have the full concentration in doing what we need to do at that point, and they scored the second one. And after that it was not good enough."

The result left Barcelona trailing LaLiga leaders Atletico Madrid by eight points.