(Reuters) - 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.
Gabriel and Mohamed Elneny scored in the closing stages to seal the win for the Premier League club.
Arteta, who took charge in December 2019, said he can see how much progress his side have made but Thursday's game had shown how the top teams punish mistakes.
"So, if we're going to go to the next level we have to stop that and be more ruthless," he added. "When you're that dominant and playing that well just kill the games."
Arteta, whose side are 10th in the Premier League, said many of their problems were self-inflicted.
"That's positive because the moment we stop it we're going to be a lot stronger," he added.
"But the reality is we have to stop immediately because if not the games are all the time there to drop points."
Arsenal take on London rivals Tottenham Hotspur in the Premier League on Sunday before hosting Olympiakos in the return leg next Thursday.
(Reporting by Shrivathsa Sridhar in Bengaluru; Editing by Peter Rutherford)