The Germany international missed a penalty against Bayern Munich on Wednesday night, leading to some negative reports.
But Sagna insists the 25-year-old remains a key player and will soon answer his critics.
He is a quality player, as he has shown before, and he is really important for the teamBacary Sagna
“It is a bit harsh on him, because since he came he has played every game and physically when you play every three days it is very difficult, especially in England,” the defender told Arsenal Player.
“The rhythm is crazy, especially when you play further forward - you have to repeat performances and at this level it makes things a bit more difficult.
“It is difficult because when you miss an opportunity because you think about it for a long time, it stays in your mind and you can’t delete it. The best way to do it is to score as soon as possible and keep your focus.
“He is a quality player, as he has shown before, and he is really important for the team.”
Sagna is looking forward to getting back to Premier League action against Sunderland on Saturday, and believes Arsenal can have a successful end to the season.
“We want to be champions, so we have to be ready and fight 100 per cent in every game, every competition,” he said.
“I am convinced we can win the league and we can win the cup as well. But we have to make a lot of effort.”Copyright 2017 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source