Manchester United had a representative at the Estádio do Dragão alongside scouts from 17 other foreign clubs, just days before facing Manchester City themselves this weekend.
While the timing invites an obvious explanation, the presence of so many overseas observers points more towards recruitment than direct preparation, with United having been linked with several Porto players over the past year. Everton were also among the numerous sides with a scout in attendance, alongside Brentford, Nottingham Forest and Ipswich Town from the Premier League, and clubs including Bayern Munich, Atlético Madrid, Paris Saint-Germain, Atalanta, PSV Eindhoven and Saudi side NEOM from further afield.
Manchester City ran out 2-0 winners thanks to an Erling Haaland double, but the scoreline flattered Enzo Maresca's side according to A Bola's player ratings, with goalkeeper Diogo Costa the standout performer of the night.
Maintaining his World Cup form, Costa produced a string of saves that prevented two or three clear goals before half-time alone, offering any watching United scout a strong demonstration of a player already linked with Old Trafford last year.
Gabri Veiga also caught the eye with his work off the ball, chasing City's midfielders throughout despite receiving little support once Porto won possession back, while Pepê and William Gomes, both previously linked with United, were also in action, though all four rank among the pricier members of Porto's squad.
It remains unclear exactly who Everton's scout was there to watch, given David Moyes's side are unlikely to have travelled simply to see City. Should full-backs have been the priority, Martim Fernandes and Alberto Costa both had underwhelming nights, while André Silva, the most plausible striker option if City's own forwards were not the target also struggled.
Porto's best performers on the night besides Costa were Kiwior and Veiga, though neither a central defender nor central midfielder appears to match Everton's most pressing needs. One theory offered a lighter explanation: that Everton's scout may simply have been keeping an eye on former player Iliman Ndiaye, who came off the bench for City.