By Sean Walsh Mauricio Pochettino has opened the door to managing either Real Madrid or Manchester United one day, insisting he believes that opportunities to do so will come around again. The Argentine has been out of a job since being sacked by Paris Saint-Germain at the end of the 2021/22 season, bringing an end to a mixed 18-month spell in the French capital. Prior to PSG, Pochettino rose to global fame as the manager of Tottenham, taking them from the fringes of the top six to Premier League title contenders and leading the club to their first ever Champions League final. During his five …