INTERLAGOS, Brazil - Ron Dennis did not attend a farewell party for Lewis Hamilton in Austin after his US Formula 1 GP win and will not be in Brazil for his former protege's last race for McLaren.The news adds to the perception that Hamilton - nurtured through his formative years by the McLaren supremo and brought into F1 in 2007 - and Dennis have fallen out badly over the 27-year-old's defection to Mercedes.NO VICTORY T-SHIRTReferring to a farewell party in Austin, Daily Mail journalist Jonathan McEvoy wrote: "Dennis instead chose to attend what a team spokesman described as 'an important cocktail reception hosted by Exxon Mobil executives at which he was guest of honour'."But after Hamilton won the US GP Dennis refused to wear McLaren's customary 'rocket-red' victory T-shirt. And the 65-year-old "has decided not to travel to Sao Paulo for Hamilton's farewell race".Dennis told Sky TV in Austin: "Obviously the media thinks there's some issue between Lewis and me - there's absolutely no issue between us. Sometimes the circumstances in a relationship don't balance, don't match."But there are rumours Hamilton and Dennis fell out very badly over the negotiations for a new driving contract for 2013 and beyond.An unnamed “senior figure” told the Daily Mail: "I do know what has happened."Everyone makes mistakes and Ron made a mistake. Everything went pear-shaped and I don't think it would be fair to say any more than that."A McLaren spokesman responded: "Ron and Lewis plan to get together socially in the near future, as they've both said a number of times recently."