Sky Sports pundit Gary Neville believes that Manchester United should feel heartache and pain over Liverpool's Premier League title-winning season.
Liverpool secured their 20th league title with four games to spare following their 5-1 win over Tottenham Hotspur on Sunday afternoon.
The Premier League title takes Liverpool level with Manchester United and with the current gulf in quality between the two teams, Liverpool could once again open up a gap at the top of English football.
Neville was a mainstay of the Manchester United side that enjoyed so much success under Sir Alex Ferguson, who delivered on his promise to 'knock Liverpool off their perch'.
On the day that Liverpool secured the title, Neville told Sky Sports that its a big moment and one that is painful for his old club.
Neville said: "It's a massive deal. When you think of the league title and the importance of the league title, you think of the great managers that Liverpool have had in Bill Shankly and Bob Paisley, Kenny Dalglish, Joe Fagan, and at United as well, talking about the importance of your bread and butter being the league title."
"The accolade of the most successful club, you could debate it, maybe when Manchester United were on 20 titles and obviously Liverpool do have more European Cups but once Liverpool get level with Manchester United, the painful thing to say is that unfortunately the debate is over until Manchester United become successful again and win leagues.
"It should cause real tremors over at Old Trafford, the idea that Liverpool, which is obviously a great football club and now the most successful club and will be after today, in English football, that really should cause heartache and pain.
"It took a lot to get ahead of Liverpool, they were miles ahead when Sir Alex Ferguson took over."