Within hours of Liverpool losing 1-0 at Sunderland last week courtesy of a goal deflected in via a beach ball thrown on to the pitch by a fan, the Liverpool club shop's entire stock of the inflatables had sold out after a rash of internet orders.
Gleeful Man Utd fans, never slow to glory in the struggles of their north west rivals, are presumed to have been behind the sales surge and Anfield stewards will be primed to keep the balls at bay during Sunday's match.
It would mark Liverpool's worst run for more than half a century and leave them 10 points behind United and potentially nine behind Chelsea, who host Blackburn Rovers on Saturday.
The club's fans are famed for the support they give their side and their manager but sections of the crowd booed the team off after Tuesday's Champions League defeat by Olympique Lyon, having also jeered Benitez after he replaced goalscorer Yossi Benayoun with Andriy Voronin late in the game.
Steven Gerrard, who lasted 25 minutes of the game after a premature comeback, Fernando Torres, Albert Riera and Glen Johnson are all struggling to make Sunday's game, piling the pressure on Benitez.
"I cannot remember an injury situation like this," he said.
"I have no idea what team I can put out against Manchester United until we have had the players tested and seen by the medical team."
