Bukayo Saka admitted Arsenal were a long way from their best after they snatched a 1-0 win away to Manchester United in their Premier League opener on Sunday.
Riccardo Calafiori got the only goal in the 13th minute when he pounced on an error from United's stand-in goalkeeper Altay Bayindir .
But Arsenal were otherwise second best at Old Trafford, sloppy in possession against a United side who impressed with their energy and purpose, even if they ultimately could not find an end product.
If the Gunners are to take a step forward this season, after three consecutive second-placed finishes in the Premier League, they cannot afford too many more displays like this one.
"It was not a great performance," Saka said. "We are happy with the three points, to come away from Old Traff