Stoke City star Xherdan Shaqiri claims Manchester United's defence is "vulnerable" following the Potters' 2-2 draw against the Red Devils at the bet365 Stadium on 9 September.
Eric Maxim Choupo-Moting opened the scoring for Mark Hughes' side before Marcus Rashford equalised for the Red Devils just before the end of the first half. Romelu Lukaku gave Jose Mourinho's side the much needed lead in the second half.
However, it was Shaqiri's corner allowed Choupo-Moting to score the equaliser as Stoke settled for a point against United. The Switzerland international's former club Basel will take on the Red Devils in the Champions League clash at Old Trafford on Tuesday.
The former Bayern Munich forward has urged Basel to take advantage of United's vulnerable defence when they take on the Red Devils in the European fixture.
"You have to play bravely. It doesn't matter if you're setting up to sit deep for 90 minutes. They have so much class in attack, sometimes they'll just shoot and score a goal," Shaqiri told Blick, as quoted by the Daily Mail.
"If they do [have a weakness], it's in their defence. That's what our goals have shown. If you play fast and bravely, the defenders have problems. At the back, Manchester are vulnerable.
"It will be extremely difficult for Basle. Especially at Old Trafford, where Manchester are far more dominant than away. Then there's the atmosphere there. Old Trafford is one of the best stadiums in the world.
"Raphael Wicky has to be brave, to risk something. Just defending won't be enough. But he probably knows that himself."
Eric Bailly and Phil Jones are suspended for the clash against Basel. The former Real Madrid and Chelsea manager has already confirmed that Chris Smalling and Victor Lindelof will start against the Swiss outfit in the heart of United's back four.