Sa huling karera ng 2005 Shell Super Kart Series sa Carmona, Cavite, lamang ng 12 puntos ang Filipino-Italian sa kanyang karibal na si Michelle Bumgarner Hindi niya kailangan pang manalo ng huling karera upang mapanatili ang kanyang titulo. Pandagdag ito sa kanyang pagiging Asian Karting Championship runner-up ng tatlong ulit, at pagiging kauna-unahang Pilipino na makakuha ng dalawang korona sa isang taon, sa Intercontinental A Class Open Championship at Junior Rotax Championship noong 2004 nang siya ay 14 lamang.
Maagang sinimulan ang huling karera nang walang sabi-sabi. At hindi pinakinggan ang pakiusap ng bata na bigyan lamang sila ng dalawang minuto upang makapaghanda.
"There’s usually a briefing before each race, but this time, there wasn’t," sabi ni Guidicelli sa mga media sa Manila Hotel noong Huwebes. "We asked for a two-minute extension, so I could warm up my kart. They didn’t allow it."
Dahil dito, nahuli ang kampeon nang magharurutan ang kanyang mga kalaban. Dala ng pagnanais na magtagumpay, unti-unti niyang hinabol ang mga kalaban. Nang malapit na siya sa mga nangunguna, may isa pang nanghihimasok upang patayin ang kanyang pag-asang makaulit pa bilang Karter of the Year.
"After moving up into fourth, the leader’s teammate who was in no way in contention for the championship and who was sponsored by the leader’s team just before the final race, bumped me from behind after I had already successfully completed an overtaking maneuver, in what certainly seemed like an intentional and dangerous move," pahayag ni Guidicelli. Hindi pinarusahan ang nakabangga sa kanya.
"Matteo is a good kid, and not to brag, but he’s done so much for the sport," sabi ni Joji Dingcong manager ni Matteo. "With all his endorsements and exposure, he has brought a new popularity to the sport. It is a shame that everything he has worked for over one year can be lost in one day, an unfairly."
Sa katunayan, kaya daw tinatanggap ni Guidicelli ang mga commercial na ito ay bilang tulong sa kanyang mga magulang, na gumagastos ng milyun-milyon sa pagpondo sa kanyang pangangarera. Ayon sa iba, ang di-magandang pakikitungo sa batang Matteo ay bilang paghiganti sa prangka nitong amang si Gianluca, na walang inuurungan kapag may napapansing sa pananaw niya’y di tama.
"If the reforms we want implemented are not made, then we will no longer participate in local races," dagdag ng dating triathlete na si Noy Jopson, assistant manager ni Guidicelli. "We will have to compete in races where that particular Clerk of Course is not involved, or compete internationally."
"But I will always carry the Philippine flag wherever I go," pagdidiin ng bata. "I feel sad that what I worked for was taken away from me, but I will also proudly compete as a Filipino, in races where I feel I will be treated fairly."