Andy Robertson prompted huge cheers from the Liverpool support as he embarked on a trademark thrust beyond several players down the left flank into the penalty area.
Divock Origi drew a free-kick in a dangerous position after his pace and raw strength saw him power past his marker.
And Jordan Henderson drove forward to accept a backheel from Mohamed Salah before playing a reverse pass to his team-mate.
Only the last action resulted in a goal, Salah finding the bottom corner to net his 17th of the season and secure a 2-0 Champions League win for Liverpool at home to Porto on Wednesday evening.
Collectively, though, the almost instant impact of those three substitutes represented something Jurgen Klopp hopes has far greater resonance than the Egyptian’s game-clinching strike.
Liverpool may have already earlier this month booked their place in the knockout stages as Group B winners, but it would be wholly wrong to suggest there was nothing at stake at Anfield.
Not least because visitors Porto were hellbent on avenging their 5-1 home humiliation to Klopp’s side in September while keeping alive hopes of snatching second place behind the Reds.
But that Liverpool, after some initial teething troubles, were able to adjust to the changes to their starting line-up and routinely dismiss the Portuguese side underlined a key tenet that was put to a genuine test in midweek.
There’s no such thing as a game that doesn’t matter to this squad. Not when there are first-team places at stake.
Klopp now has the genuine competition for places throughout his team he hopes will give him the kind of headache he wants as Liverpool embark on the long slog towards 2022.
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Wednesday’s match was the second of 13 in 44 days, a spell which began following the recent international break and culminates with the Premier League trip to current leaders Chelsea on January 2.
Ten matches come in the top flight, a sequence that will go some way to determining the genuine strength of their title challenge this season.
Nobody will start all 13. Joe Gomez, Curtis Jones, Naby Keita, Roberto Firmino and Harvey Elliott were all sidelined on Wednesday and the winter grind ensures more will follow them on to the treatment table.
And that’s what has made making the most of opportunities an imperative for both the team and the individual.
It was revealing key players such as Robertson and Henderson were determined to make their mark against Porto.
Robertson, while recently nursing a minor hamstring problem, saw debate sparked among a section of Liverpool fans over his position as first-choice left-back following a clutch of encouraging displays by Kostas Tsimikas.
The Scot’s midweek cameo – bright, busy and productive – did not pass unnoticed.
Neither did the impact of Henderson who, having come off the bench to play a part in the build-up to Liverpool’s third goal against Arsenal at the weekend, claimed his third direct assist of the campaign.
The skipper, also troubled by an injury niggle during the international break, has witnessed Fabinho, Thiago Alcantara and Alex Oxlade-Chamberlain all impress in his absence from the starting line-up.
Origi, meanwhile, has had game time limited for Liverpool this season but has registered three goals and two assists in 291 minutes for the Reds, form that saw him recalled to the Belgian national team this month.
That Takumi Minamino, another to have made good use of his game time, was given a start against Porto will surely have acted as further motivation.
This all matters, as does a confidence-bolstering outing for Neco Williams and an encouraging European debut for teenage midfielder Tyler Morton.
With three midweek Premier League games incoming along with the final Champions League group match at AC Milan and the Carabao Cup quarter-final at home to Leicester City, every player is going to be needed.
And Klopp, keen to maintain Liverpool’s rhythm, knows it’s a lot easier to step into a winning team – and equally as difficult to play yourself out of one.