Arsenal have made great strides in the past year but must learn to cut out the mistakes if they are to reach the next level, manager Mikel Arteta said after Thursday's 3-1 Europa League victory at Olympiakos.
Arsenal went ahead in the first leg of their last-16 tie through Martin Odegaard's first goal for the club but an error from Hector Bellerin saw Youssef El Arabi make it 1-1.