Manager Arsene Wenger says Arsenal "have to be patient" with new signing Danny Welbeck after his miss proved costly in the 2-0 Champions League defeat at Borussia Dortmund.
The 23-year-old England forward, a £16m arrival from Manchester United this month, shot wide when in a good position to score at the time the Group D game was goalless.
Dortmund scored either side of half-time to secure victory.
"Danny will improve - we don't have to make a problem of that," said Wenger.
Welbeck scored both goals as England beat Switzerland 2-0 in a Euro 2016 qualifier on September 8.
But he has not found the net at club level since scoring for United in a 3-0 Premier League win at West Brom on March 8.
