Marc Guiu has been one of the biggest surprises of Chelsea’s pre-season this summer, but is he ready to be thrown in for a competitive debut this weekend? Chelsea kickstart their Premier League campaign on Sunday afternoon by hosting reigning champions Manchester City. For Blues head coach Enzo Maresca, he couldn’t have had a tougher introduction to the new season. Marc Guiu, who’s just 18, has really caught the eye during the last month. He’s arrived from Barcelona in this transfer window as an upcoming talent and looked at home immediately around the Blues first-team group. When it comes to …