Liverpool will need to bounce back quickly from two poor performances and results in the Premier League and the Champions League when it visits Chelsea this weekend.
And Arne Slot will have a few decisions to make when it comes to his team selection. Ibrahima Konate was poor again in Istanbul while there remains question marks over how Florian Wirtz fits in, and Jeremie Frimpong struggled to make an impact as he filled in for Mohamed Salah on the right wing.
Here is how the UK's national media rounded up the action in Turkey as Liverpool suffered a setback. Fortunately, Slot's men have another six games left to ensure they progress into the knockout phase.
BBC Sport: "One of the major sources of concern in Liverpool's season so far is the lack of impact from Wirtz. Here is a player clearly rich in talent and pedigree, who attracted strong interest from Manchester City before choosing Liverpool.
"He was the Bundesliga's golden boy after his development under Xabi Alonso at Bayer Leverkusen.
"Wirtz is playing in a withdrawn role behind Liverpool's striker — Ekitike in Istanbul — but apart from one shot in the first half that forced a save from Galatasaray keeper Ugurcan Cakir, he was once more peripheral. It left him still seeking his first Liverpool goal.
"Even the best players sometimes need to bed in, with Wirtz getting to know his team-mates and his team-mates getting to know him, but Liverpool will hope for a spark of inspiration for their £116M ($157M) man sooner rather than later."
The Times: "Flawless, Liverpool are not. In the space of a few days, lingering concerns are now stepping out of the shadows for the champions.
"After stumbling at Crystal Palace, Arne Slot’s side wilted in Galatasaray’s deafening cauldron, coughing up too many mistakes and falling to defeat thanks to Victor Osimhen’s penalty.
"Soft as it was, this was not a game in which Liverpool could confidently say they deserved victory and they now face up to back-to-back defeats, and for Slot, some issues to resolve.
"Concerns that were whispered quietly amid a fast start in the league were all loudly evident in Istanbul. How do they bed in their new arrivals?
"How to get the best out of Florian Wirtz? What is the root cause of so many defensive lapses that meant six clean sheets from their first ten games last year have slipped to only two this year? Who are their best full backs?
"Galatasaray are, of course, not a bad side, winning three straight Turkish league titles and spending £65million on Osimhen — the standout performer on the night.
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"But Europe has proved a different story; they failed to get past Young Boys in last season’s Champions League play-offs and in their first game of this tournament they were humbled 5-1 by Eintracht Frankfurt. Liverpool’s quality gap should have been more evident."
The Telegraph: "After 15 months when everything Arne Slot touched turned to gold, we will now have to see a different side to the Dutchman. His decisions here in the manic cacophony of RAMS Park backfired as his Liverpool team slipped to consecutive defeats.
"Slot decided to leave Mohamed Salah on the bench for an hour, by which time Galatasaray had momentum in the game through Victor Osimhen’s first-half penalty.
"The Liverpool coach also deployed Jeremie Frimpong as an attacker rather than his right-back position, with Dominik Szoboszlai dropping into the back line and conceding the winning spot-kick.
"None of this feels hugely concerning, with Liverpool still top of the Premier League, yet there is clearly work to be done in a season where Slot’s team have lost control of games or, in this case, succumbed to slick opponents.
"After defeat at Crystal Palace at the weekend, facing Chelsea on Saturday will be another big test."
Daily Mail: "There was no miracle of Istanbul this time, 20 years on from Liverpool’s most famous night in this charming city on the banks of the Bosphorus, but they will need another minor miracle to win the Champions League again this year if they defend like this.
"‘Miracle’ is a bit strong but Arne Slot knows his Premier League champions are a shadow of their former selves at that end of the pitch and must improve if they want to be crowned kings of the continent in May.
"There is no need for panic — this was a poor display but by no means a disgrace, and plenty of teams have wilted in this melting pot by the Marmara Sea. But Liverpool will have boarded their plane home knowing they need to improve tenfold at Chelsea on Saturday.
"The chief concern was that it all felt too similar to last weekend when they lost at Selhurst Park — and not just because of the raucous, hostile welcome (sorry, Palace fans, but the noise here made the sound of the Holmesdale Fanatics feel as calming as a meditation session).
"There were some bright moments but the Reds were crying out for some of their substitutes, most notably Mohamed Salah who started on the bench in a meaningful Premier League or Champions League game for the first time since a row with Jurgen Klopp in April 2024.
"Despite all the money spent this summer, Salah is still the main man at the club even though it is fair to describe his start to the season as underwhelming. The sight of him and the small matter of £125m Alexander Isak warming up must be anxiety-inducing for opponents.
"What is more anxiety-inducing at the moment, though, for Liverpool fans at least, is the form of the defenders, chiefly Konate. The Frenchman was solely at fault for giving the ball away in his own half in the second half, with Osimhen allowed to charge through on goal."