Harry Kewell rejected the chance of a move to Manchester United because he wanted to join a club that is "on the up", according to his agent.
The Australian completed an acrimonious £5m move from Leeds United to Liverpool last week.
And his agent, Bernie Mandic, confirmed Kewell had been targeted by Manchester United and Chelsea, among other clubs.
"It happened to Liverpool from the mid-1980s onwards, when they started to splutter and the success started to drop off - since 1990 they haven't won a title," Mandic told Garry Richardson's Sportsweek programme on BBC Radio Five Live.
"I think Manchester United are destined to go into a downturn.
"Harry signed a five-year deal with Liverpool and wanted to go to a team that's on the up."
Kewell's move to Anfield caused considerable controversy as Leeds claimed they were forced into a situation where they made just £3m for a player valued at 10 times that amount a year ago.
Mandic described as "far-fetched" the suggestion that he personally had earned £2m from the deal, but admitted that was the fee paid to his company MaxSport.
"What Leeds haven't revealed is that MaxSport was meant to receive 50% of anything over and above £5m," said Mandic.
"If we'd have sold Harry for £9m, MaxSport would have received £4m. At the end of the day, Leeds made that deal.
"When we talk about blackmail, what was put to us was 'if you want Harry to walk away with his head held high and for the supporters to continue to view him as a Leeds hero, you've got to take our deal."