Chelsea boss Jose Mourinho rates last season's title triumph his "toughest".
In an interview for the Premier League Season Review 2014/15, Mourinho spoke of how competitive the league is.
"It [the Premier League] is more difficult than ever, I would say it was the most difficult one. It's very competitive with good teams.
"The mentality is very important and in this country even the teams without the same human potential as the top teams really fight and really believe. Every game becomes very competitive and mentality is a big part of it.
"At the same time, the good financial situation that every club has allows even the smaller teams and the promoted teams to get good players, have good squads and to be competitive."