A "major gamble" was taking place on Wednesday afternoon on Gus Poyet becoming Chelsea's next manager.
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Coral suspended their market following "a surge of bets online" but at 1500 GMT BetVictor are still up with 3/1.
Both firms were offering 25/1 on Wednesday morning.
Sky Bet moved their price in from 12/1 to 6/4 in just half an hour, while Stan James went 11/10 from 10/1.
Former Chelsea star Poyet, currently in charge at Brighton, replaced Jose Mourinho as the market leader as a result of the gamble.
Coral's Simon Clare, who revealed one of the bets placed with the Stratford-based firm was £1,000, said: "When it comes to these markets there is rarely any smoke without fire and the sudden surge of bets on Poyet suggests something significant may have gone on in the Chelsea boardroom."
Sky Bet's Stuart Dallimore added: "We had several bets around the same time for Poyet to be the next Chelsea manager, most of which were to new accounts who were hitting their maximum.
"It's hard to say whether the money is from people who know or whether it's just a bit of a bandwagon punt.
"We're still wanting to keep Mourinho fairly short as that would be the choice for the fans and the person who Abramovich should appoint if he wants to win back some of the fans."
Current interim boss Rafael Benitez has shortened significantly in the Premier League 'sack race' market in recent days following the Blues' 2-2 FA Cup draw at League One Brentford on Sunday.
The former Liverpool manager was not a popular appointment with the club's fans.
He has since won 10 of his 19 games in charge, although significantly Chelsea's home record under him is just three wins in eight.
A move for Poyet may prove popular with some supporters but his lack of experience as a manager at the highest level - he has yet to manage in the Premier League - would doubtless worry some.