Bookmakers are expecting to take a small fortune when David Haye clashes with Wladimir Klitschko on July 2.
Haye will meet the Ukrainian giant in Hamburg in the most eagerly-awaited heavyweight fight for years.
And Hills alone are expecting to turn over a cool £5million for the big showdown in Germany.
The Leeds-based firm say the vast majority of bets so far have gone on a Haye victory (11/8), while Klitschko remains their 4/7 favourite.
They say biggest liabilities are for the Brit to win on points at 7/1, or Klitschko to prevail inside a round (20/1).
Spokesman Joe Crilly said: "We are expecting turnover to reach £5million and we appear to be well on the way to that target. As it stands, a Haye victory would be a huge KO for us."
Meanwile, Coral make Klitschko a 1/2 favourite, with Haye a 6/4 chance and the draw 28s.
Spokesman Gary Burton said: "Although we make Klitschko the favourite, we expect to see a closely-fought contest, and with betting available throughout the fight, the longer it goes the better.
"We expect business to exceed the Hatton-Pacquiao fight of two years ago, meaning an industry turnover in excess of £5million."
Bet365 say that punters are betting with their heads rather than their hearts, with most plumping for a Klitschko victory (8/15 from 4/7).
Spokesman Steve Freeth said: "David Haye has beaten the odds before, but there aren't many punters in his corner for the bout against Wladimir Klitschko - 90 percent of the business we've taken is for the big Ukrainian."