Talks between Manchester United and Chelsea over the transfer of Juan Mata are going well, Sky Sports understands.Meanwhile, Sky Bet continue to see support for Mata to leave Chelsea before the end of the transfer window. As of this morning the diminutive Spaniard was as short as 4/7 with online bookmaker Sky Bet to join Manchester United after starting the week as an 11/2 chance and turning the year at 25/1! Sky Bet football trader Joe Petyt said: "We'd seen a few bets at big prices over the last month or so but on Sunday night the types of bets we were taking changed. "We saw a few maximum bets at 11/2 and ever since customers have been taking whatever price we put up. He's now just 4/7 but that still hasn't put people off getting as much as they can on the move going through, " he added. It would appear to finally signal a change of heart from the Chelsea hierarchy to the possibility of letting their popular player-of-the-year for the past two seasons move on. This has led to Sky Bet opening a stay/go market and it's 8/15 that he will leave before the end of the current window and 11/8 that he stays. One other possible option for Mata as he seeks to put himself in the frame for World Cup selection with Spain is a return to his homeland, possibly on loan. It's 20/1 that his destination is Atletico Madrid as they chase the La Liga title.