Liverpool dented Porto's bid to qualify for the Champions League last 16 as Thiago Alcantara's first goal since May inspired a 2-0 win on Wednesday.
Jurgen Klopp's side had already booked their place in the knockout stages as Group B winners, but they did not rest on their laurels at Anfield.
Thiago has endured a difficult time with Liverpool, struggling to recapture the form that made him a Champions League winner at Bayern Munich.
The Spanish midfielder gave a glimpse of his talent with a composed display capped by a blistering long-range strike to put Liverpool ahead in the second half.
Mohamed Salah sealed Liverpool's fifth successive group victory with his 17th goal this season.
Porto are second in the group, one point ahead of Atletico Madrid and AC Milan, leaving Sergio Conceicao's team needing to beat the Spanish champions in their last match on December 7 to advance alongside Liverpool.
With Liverpool qualified in their previous game, Klopp could afford to rest some of his key players at the start of a hectic winter schedule.
Liverpool do not have an empty midweek left in 2021 and face nine games in all competitions in December.
"In this time of the season, the medical department has a big hand in line-ups," Klopp said this week.
Liverpool's 19-year-old midfielder Tyler Morton made his Champions League debut, with Neco Williams, Ibrahima Konate and Takumi Minamino also coming in.
Morton's first-team debut only came in September, while he made his first Premier League appearance as a late substitute against Arsenal at the weekend.
Klopp says Morton has "all the tools" and he did not look out of place on the big stage.
Porto were inches away from taking the lead when Otavio robbed Kostas Tsimikas and whipped a cross towards Mehdi Taremi, whose header hit Joel Matip and deflected just wide.
Moments later, Luis Diaz's deft pass picked out Otavio's run into the Liverpool area, but Tsimikas made a lunging last-ditch tackle that forced the midfielder to poke wide.
Porto suffered a blow when their veteran defender Pepe saw his 100th Champions League start curtailed by an injury midway through the first half.
Liverpool should have gone ahead when Salah produced a tame finish after Porto keeper Diogo Costa miskicked a clearance that cannoned off Sadio Mane's face to the Egyptian.
Mane thought he had scored in the 37th minute when he ran onto Thiago's pass and slotted home, but a VAR check showed the Senegal forward was marginally offside.
When Mateus Uribe swivelled to fire just wide soon after half-time, it seemed Porto were beginning to take control.
But it was Klopp's men who made the breakthrough thanks to Thiago's moment of magic in the 52nd minute.
Alex Oxlade-Chamberlain's free-kick was headed out to Thiago and he drilled a superb 25-yard drive past Costa.
Oxlade-Chamberlain went close with a long-range rocket before Thiago was substituted to a standing ovation from the Kop.
Thiago's replacement Jordan Henderson set up Liverpool's second goal in the 70th minute, picking out Salah, who shimmied inside before planting a low strike into the bottom corner from 12 yards.