After the Old Trafford side wrapped the title up with four games left to play, McClaren has suggested that losing the trophy to Manchester City last season provided the best motivation.
"That devastation after losing the title on the last day of the season by one minute gave him the motivation he needed," McClaren told BBC Radio Five Live.
"By attitude in every game they have won it. He knew what was missing last season, he knew it was a goal scorer, a special player for Manchester United. He's got that in Robin van Persie and he proved that last night."
Van Persie is favourite to clinch the golden boot as he currently sits on one more goal than Liverpool striker Luis Suarez.