Manchester City midfielder Yaya Toure has said in The Sun that Manchester United are "really struggling" under manager David Moyes.
United have begun the defence of their Premier League title with just four wins from their opening nine matches of the 2013-14 season.
The Red Devils trail leaders Arsenal by eight points, though seventh-placed City sit just two points above Moyes' side in the standings.
Regardless, Toure doubts if United can retain their crown and instead has tipped Liverpool, who are currently third, as a force to be reckoned with.
He said: "United will find it hard to defend the title since they have a new manager and are really struggling.
"Liverpool are a big threat at the moment because they have a strong squad and their strikers -- Luis Suarez and Daniel Sturridge -- are scoring goals at will."
Toure also gave his backing to goalkeeper Joe Hart, whose place in the side has been up for debate following his mistake in the 2-1 loss at Chelsea.
The Ivory Coast international added: "Joe is a top keeper who gives his all to the team."