Granit Xhaka's challenge is to graft himself onto a team which are in the ascendancy; Arsenal's challenge as a whole is to sustain that trajectory.
Brendan Rodgers wanted the Man City job but now finds himself at Celtic. His new club has a lot to prove vs. Pep Guardiola, writes John Brewin.
PSG arrive in Bulgaria to face Ludogorets Razgrad on Wednesday with one point to their name -- the same as the rest of Group A.
ESPN FC's Brian McBride and Alexis Nunes give their predictions on Wednesday's matchday 2 fixtures.