Sky Bet have cut the odds on the striker moving to Stamford Bridge from 11/2 to 1/2, while the odds on him remaining at Manchester United have drifted out to 13/8, having been as short as 1/5 after David Moyes initially insisted that he is not for sale.
Rooney is reportedly "angry and confused" about his treatment by the club after Moyes followed up his insistence on holding onto his services by commenting: "I won't allow Wayne Rooney to become more important than the football club."
Jose Mourinho has confirmed his admiration for Rooney since returning to Chelsea, with the Blues reportedly having a bid of £10m plus either Spanish playmaker Juan Mata or Brazilian defender David Luiz.
Sky Bet have consequently slashed the odds on Mata moving to United from 20/1 to 6/4, while Luiz is currently 8/1 to head to Old Trafford.
Sky Bet Football Trader Chris Spicer said: "We were convinced that Rooney would not be allowed to leave after Moyes laid down his initial stance, but his recent comments are somewhat confusing.
"Relations are starting to appear irreparable and we have now installed Chelsea as the favourites for the Premier League at 9/4, which would shorten significantly if they secure Rooney's services."