Liverpool legend John Barnes insists the club's American owners must keep their promise to back Rafael Benitez in the summer transfer market if they are to challenge league champions Manchester United and Chelsea.

Benitez has already implored George Gillett and Tom Hicks to provide the $134 million transfer fund promised when the duo completed their $650 million takeover in February, following the Reds' Champions League final defeat by AC Milan and third place showing in the Barclays Premiership.

Hicks owns the NHL's Dallas Stars and the Texas Rangers in major league baseball. Gillette owns the NHL's Montreal Canadiens.

Barnes believes Benitez halready built the foundations of a team capable of challenging for the title in his three years at Anfield, and claims that a small number of "quality" signings will help to reduce this term's 21-point deficit to United.

Atletico Madrid skipper Fernando Torres, fellow strikers Samuel Eto'o, Carlos Tevez, David Villa and Dimitar Berbatov, Real Zaragoza's Argentina defender Gabriel Milito, Benfica captain Simao and Brazilian right-back Daniel Alves are among the names linked with summer switches to Merseyside.

"I'm sure if those players are available, Manchester United, Chelsea and Arsenal will also be after them," Barnes told PA Sport.

"Whether they come to Liverpool or not I don't know, but that's the type of quality they should be looking for, who can come and go straight into the team and not just be a squad player. There is not a single important area. You are not going to buy one player and close a 21-point gap, you need more quality in the team in every department, particularly up front."

Barnes was part of Liverpool's last championship success in 1989-90 and is desperate to see this season's huge gap to Sir Alex Ferguson's Red Devils reduced next time out.