Times have been tough at Manchester United, and the lack of goals have put Lukaku in the spotlight for some fans.
"I feel sorry for him, they don't play to his attributes," Murray said in an appearance on 'Sky Sports'.
"With Manchester United you've got wingers coming in and shooting which is not ideal for a player of his ilk.
"But he's a guaranteed 20-goals a season. He's maybe hit a little bit of a dry patch at the minute but he will come good.
"He's shown his class time and time again