He said: "The top four are very strong. People suggest Arsenal may slip out of the top four but I don't go along with that view. They are a top-quality side still.
"There's a lot of money sloshing around but more often than not the big four get the majority of it and so that does have an impact.
"When the champions of the Premier League are investing significant amounts that tells you that even when you are strong you still have to strengthen.
"United are champions and they are used to having the gold lion on their sleeve.
"They have defended their title well in the past and it will be a good team that beats United - but plenty of them want to do it."