The fight will take place on April 3 at the MEN Arena, where the American is 7/2 at Boylesports to come out on top.
Skybet make Haye, who will making the first defence of his WBA heavyweight title having won it by beating Nikolai Valuev in November, 5/1 to knock out his opponent.
Sky Bet’s boxing expert Simon McMinn said: “David Haye will be going back to doing what he does best by throwing big punches at Ruiz. He had to box clever against Valuev but expect him to add to his impressive list of knockouts.”
Of his 23 fights, the London boxer has won 21 by technical knockout and Skybet offer 11/8 about him adding to this tally and 9/1 that he wins by a split decision.
Meanwhile, Ladbrokes offer 25/1 that Haye holds all four major heavyweight belts (WBA, WBC, IBF and WBO) by the end of the year and 4/1 to do so by the end of 2011.