 Xavier enjoyed a productive and ultimately successful development into a senior player with BSC Young Boys, playing with the youth teams of his hometown club FC Onex and then later Etoile Carouge.Between 2005 and 2006, he also spent one year on the books of Swiss giants Servette, scoring 31 goals in 68 games whilst playing as a winger for their reserve team but failing to make the grade as a senior with the club.Xavier's form with Servette's B-team attracted the attentions of BSC Young Boys, who upon learning of Servette's plans to release him at the end of the 2005/2006 Super League season signed the teenager on a free transfer in June 2006.