"We could have taken a giant step tonight," he said. "That they scored their second goal out of nothing was very disappointing for us.
"But you know when you play here, it will get tough. In the second half it was difficult for the first ten minutes, but after that things went well again.
"They just have a lot of quality, though, so I can only be proud of my boys."
Ajax are now third in the group with four points from as many matches.