And United's midfield enforcer Anderson told The Sun: "Arsenal were much better in Italy and that is a warning to us.
"But our challenge this season is to win every point at Old Trafford and to do that we must give 150 per cent in every game.
"It won't be easy as Arsenal have had problems and will want to turn things around.
"They will play a different way without Cesc Fabregas and Samir Nasri and won't be handing us any gifts.
"And they always play their best against us. But I am optimistic if we play our usual game we will win."