Cape Town - Former Arsenal goalkeeper Jens Lehmann feels Alexis Sanchez cannot be regarded as a big player as long as he continues his "sulking" on the field.
Sanchez has often looked a frustrated figure on the pitch, getting into arguments with his teammates and not being his usual energetic self in what has been a difficult campaign for the Gunners.
The London club were eliminated from Champions League in the last 16 stage, losing 10-2 to Bayern Munich, and have dropped out of the top four on the Premier League table.
The now 47-year-old Lehmann, who reached the final of the Champions League with the Gunners in 2006, also questioned the performances of German compatriots Mesut Ozil and Shkodran Mustafi.
Lehmann told The Sun: "They talk about Sanchez being a big player but if you are sulking, you can't be a big player.
"You must be a big player mentally, not just be good at dribbling.
"There's always a question with Ozil - how much can he contribute when it gets tough?
"It's not Mustafi's fault someone has paid £35m for him. If someone buys me for £35m, the next day I'm not a better player.
"He is giving everything. But sometimes the team concede five, so he has to ask himself if it's good enough?"