German promotional company Sauerland has options over Haye and could invoke a clause that would force the heavyweight rivals to meet again.
Haye won the WBA world title from Valuev with a majority points decision in Nuremberg last November, though it was widely regarded as a dismal contest.
But Warren insists the only way Haye will fulfil his ambition is if Valuev is paid to step aside.
“If Haye beats Ruiz then Sauerland, who he’s signed a deal with, will enforce a rematch with Valuev,” the promoter said.
“I think that would be a disaster for boxing, but the rematch clause is there in the contract.
“It was a dreadful fight the first time around, I don’t care what anyone says. It was a stinker.
“Either guy could have been given the decision, it was the most boring fight ever. There was nothing to choose between them.
“One thing is sure I wouldn’t be watching the rematch, though I’m sure I could get Mogadon to sponsor them!
“I like to see a bit of action but when people are throwing 10 punches a fight, that’s not what it’s all about.
“Haye wants to fight the Klitschkos but the big hold up there is Valuev.
“The only way for Haye to get to fight one of the Klitschkos is to pay Valuev to step aside. Valuev will then meet the winner.”
Physically Haye would once again be at a huge disadvantage were he to meet one of the Klitschko brothers, having been dwarfed by the towering Valuev.
Haye insists the Klitschkos, who are one-dimensional yet very effective, are made for his style but Warren believes a suspect chin ruins his prospects against the Ukrainian brothers.
“I don’t know about Haye being the saviour of the heavyweight division – I want to see him fight the Klitschkos first,” he said.
“He had opportunities to fight both but pulled out against both, one because of injury and the other because he didn’t like the terms of the contract, even though they were exactly the same as the terms he signed to fight the other brother.
“The Klitschkos would be too big and too strong for Haye. I don’t see him beating either of them.
“They’re too big, too strong and very methodical with good jabs. I don’t see Haye even making a dent.
“They think he’s made for them because of the way he fights. If Monte Barrett can put Haye on the floor then the Klitschkos certainly can.
“A 40-year-old Carl Thompson put Haye on the floor while Enzo Maccarinelli even wobbled him in the first round of their fight in 2008.”
Haye fought the only way he could against Valuev, yet Warren insists he must look more explosive against Ruiz.
“David has secured the prize and now needs to look good. If he can’t look good against Ruiz then he never will,” he said.