Unbeaten Uzbekistani Chagaev, 30, won a majority decision over 7ft Valuev in Stuttgart in April 2007.
Valuev went on to make an unimpressive defence against four-time former world champion Evander Holyfield last December.
The 37-year-old Ruiz, who has lost twice to Valuev, stopped Adnan Serin on the undercard on Saturday.
Haye, who defeated giant Russian Nikolay Valuev in November, first faces a mandatory defence against American John Ruiz.
This was the second time the pair have clashed and the second time Valuev has beaten Ruiz on points.
But after Chagaev was named "champion in recess", Valuev regained his crown when he beat John Ruiz in August 2008.
Haye, 29, won the WBA belt by beating giant Russian Nikolay Valuev on points in Germany on 7 November 2009.
"I have to defend against Ruiz because that was part of the deal for me to fight Valuev, " said Haye.
The 7ft tall, 24st Valuev was awarded the fight with a 116-113, 116-111 and 114-113 result for his 49th professional win.
Haye rubbished Valuev's suggestions that he had spent the fight running away, adding that the 36-year-old "hadn't hurt me at any time".
Haye took the WBA title by outpointing Russian Nikolay Valuev on Saturday.
"That loss still haunts me, now is the time to finally set the record straight, " Valuev said prior to the fight being called off.
The Helenius-Gammer fight was set to take place on the undercard of the WBA heavyweight title bout between holder Nikolay Valuev and Ruslan Chagaev.
"I'd like to thank the British fans for their support, it made me feel I could not let Valuev win, " he told BBC Sport.
However, Frank Bruno hailed Haye's bravery in taking on and beating the 7ft Valuev, who had only lost one of his previous 51 fights.
Talks were then held about an autumn challenge against Vitali until Haye's camp walked away and fought Nikolay Valuev for the WBA belt instead.
The Englishman was set to fight Wladimir last year but pulled out with a back injury, later beating Nikolay Valuev to secure the WBA crown.
The 29-year-old Londoner, who used his superior movement and hand-speed to grind Valuev down over 12 rounds, said he had fought "the perfect tactical fight".
What would happen against Britain's David Haye or Russian Nikolay Valuev?
Valuev will now face Chagaev in an obligatory defence by June 2009 after the former champion was forced to relinquish his crown through injury earlier this year.
Chagaev was given the label of "champion in recess" by the WBA after he failed to defend his title on two occasions against Valuev because of injury.
First the Londoner must hope that Nikolay Valuev, the man he beat to win his title last November, will not enforce a rematch clause in their contract.
But British promoter Frank Warren does not rate Valuev and believes Haye's quality as world champion can only be judged when he faces one of the Klitschko brothers.
Haye revealed that he broke his right hand in his victory over Valuev, while Ruiz suffered a nasty cut during his win against Adnan Serin on Saturday's undercard in Germany.
Harrison is at least correct in the last part of that statement - next month Haye fights Valuev for the WBA title and, on Friday's evidence, he is Britain's best hope.
"Valuev was a great champion and an amazing attraction but today is really the beginning of a new time for the heavyweight division and the sport of boxing, " said Schaefer, who is chief executive of Golden Boy Promotions.
He visits a Russian farm to look at the country's ambitions to be an agricultural superpower, checks out the Star City astronaut training center, meets with seven-foot boxing world champion-turned-movie star Nikolai Valuev and talks along the way with entrepreneurs and environmentalists working to make the city of Sochi home to green Olympics in 2014.
He lost it again to James Toney by unanimous decision in April 2005 but the result was rescinded after Toney tested positive for a banned substance and Ruiz retained the belt as the fight went down as a no contest, only for him to lose it for the final time to Nikolay Valuev eight months later.
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