Former Manchester United midfielder Lou Macari believes that the club may struggle to keep hold of their Premier League crown.
The Red Devils have lost veterans Gary Neville, Paul Scholes and first-choice goalkeeper Edwin van der Sar to retirement this summer.
Despite Sir Alex Ferguson's spending spree in the transfer window, Macari is unsure if Ashley Cole, Phil Jones and Spanish youngster David De Gea can live up to their predecessors.
"The new players coming in at Manchester United will be looked upon as filling the boots of Edwin van der Sar, Paul Scholes, Gary Neville,” Macari told talkSPORT. “Are they capable of doing that? It's a big ask to do that.
“I don’t care who they sign. There's no player that I've seen about who can replace Paul Scholes. You can forget it; it's not going to happen. There's no goalkeeper, no matter who it is, who can replace van der Sar.”
Although the North West club are favourites to retain the title, the 62-year-old thinks it will be difficult without their former stars.
"Normally at this stage of the season, I’m looking ahead and thinking United for the title. I said it last season; I thought 'yes, they're going to do it'.
“I'm just a little bit concerned that the big guns, the lads that have done it regularly - Scholes, Neville, van der Sar - that they won't be kicking off the season. I'm going to wait and see how they start before making any predictions."
United's new campaign begins with an away trip to West Brom on August 14.
