Manchester City slumped to a second straight friendly defeat as Adriano's first-half strike was enough to hand FC Porto victory at Eastlands stadium.
Midfielder Raul Meireles' corner was headed home by the Brazilian striker -
not to be confused with his namesake at Inter Milan - just before the break.
Georgios Samaras hit the side netting when well-placed, before Helton saved from Bernardo Corradi in the first 45.
And City were again unlucky when Samaras hit the post after the break.