A Bola places Tottenham among the clubs who had scouts at the Dragão, without saying which player they were there to watch.
Porto led through Gabri Veiga's 31st-minute finish, only for Alexander Bah to level from close range four minutes after Clément Lenglet was sent off for striking André Silva. Victor Froholdt restored the lead within minutes, and substitute Hwang In-beom completed the scoring late on.
Spurs' own loanee, left-back Souza, was an unused substitute for Porto, still waiting for his debut at the club.
Froholdt, back from a concussion lay-off, was arguably the pick of the players Tottenham had reason to watch. The 20-year-old Dane drove Porto's midfield forward all evening before scoring the goal that put them back in front. Veiga, 24, also caught the eye with a clever run and cool finish for the opener, continuing a run of form that has made him one of Porto's most reliable performers this season.
Benfica had their own players worth noting. Tomás Araújo, a centre-back regularly linked with a move to England, had to marshal the defence for most of the second half with a man down, and did so better than the scoreline suggested. Gianluca Prestianni, the 20-year-old Argentine, caused problems from the left throughout and provided the cross for Bah's equaliser.
Vangelis Pavlidis did not score, but Tottenham would hardly judge him on a single evening. The Greek striker has eight goals in seven league games this season, a return that matches Spurs' need for reliable finishing, and he has been linked with the club before.
The most eye-catching return came at the very end. Samu Aghehowa, formerly known as Samu Omorodion, came on for Porto in the closing minutes, his first appearance since an ACL injury nearly eight months ago, having previously drawn Tottenham's interest with a prolific run of scoring in Portugal. There was barely time to judge his current level, but simply seeing him back on the pitch will interest Spurs' recruitment staff.
Two more familiar names were among the substitutes. Goalkeeper Anatoliy Trubin, once linked with a move to north London, has lost his starting place at Benfica after a difficult summer, while winger Andreas Schjelderup came on late without making much impact. Former Tottenham loan hero João Palhinha started in Benfica's midfield and was one of their better performers on the night, winning duels and trying to contain Porto's control of the game with ten men.