Ozil has been in fine form of late as we have reached the Europa League quarter-finals and moved up to fourth in the Premier League.
"Mesut had some small problems and he missed a few games, but he's with the team again and he's fighting," Monreal told arsenal.com. "If you see him training or playing you can see that he's completely committed to the team and that's really good.
"He's very important for us and he's a top-quality player. He helps us a lot with assists and scoring goals.
"When the other teams see him on the pitch, they say, 'Oh Mesut is here, we need to be careful' so he's an important player."