According to West Ham boss Gianfranco Zola, Arsenal and Barcelona are currently playing the best football in Europe.
In comments reported by the Daily Mirror, Zola said: "When we played Chelsea last week they probably didn't play with the same quality or intensity as Arsenal. Arsenal are terrible, if you leave them a little bit of space because they punish you."
"Arsenal, along with Barcelona, are the team who are playing the best football in Europe probably. They are very good to watch."
Zola was unsure however about Arsenal's ability to sustain their quality until the end of the Champions League campaign.
"Whether they are going to be able to do that until the end I don't know. That is the question that everybody is asking."
"Arsenal played some good football but there were some moments when we matched them completely. Arsenal and Chelsea are both good teams and they will be in contention until the end that is for sure," concluded the Chelsea legend.