The midfielder, who will join City on 1 July, helped the Selecção to a 4-0 triumph over New Zealand in Saint Petersburg, doubling his side’s lead.
Cristiano Ronaldo had opened the scoring from the spot, before Silva converted Eliseu’s cut-back on 37 minutes.
There was some concern that City’s new recruit had sustained an ankle injury as he swept the ball past goalkeeper Stefan Marinovic but after a short delay, he returned to action.
The 22-year-old - voted Man of the Match in Wednesday’s win over Russia - played another instrumental role, expertly retaining possession, driving at the New Zealand defence and threading intricate through-balls at every opportunity.
Andre Silva added a third with a fine driven finish before Nani completed the scoring for Portugal, who had only needed a draw to secure qualification but clinched top spot in their group.
Silva was brought off at half-time in what looked to be a precautionary move ahead of the semis. Stay tuned to ManCity.com for updates over the next few days.
New Zealand: Marinovic, Boxall, Doyle, Durante, Ingham, Lewis, McGlinchey, Rojas, Smith, Thomas, Wood.
Subs: Moss, Williams, Barbarouses, Brotherton, Colvey, Patterson, Roux, Rufer, Smeltz, Tulloma, Tzimopoulos, Wynne.
Portugal: Patricio, Alves, Eliseu, Moutinho, Pepe, Pereira, Quarisma, Ronaldo, Semedo, Andre Silva, Bernardo Silva.
Subs: Beto, Jose Sa, Nani, Carvalho, Pizzi, Fonte, Gomes, Martins, Neto, Adrien Silva.
Referee: Mark Geiger (USA)