The English champions were punished for the latest in a series of poor performances in Istanbul as they suffered back-to-back defeats for only the second time under Arne Slot.

Liverpool were beaten for the first time this season at Crystal Palace on Saturday, but a series of late winners have masked an unconvincing start since a summer transformation of the squad that strolled to the Premier League title last season.

Slot responded by leaving Mohamed Salah and £125 million ($168 million) signing Alexander Isak on the bench among four changes.

The Dutchman was scathing in his assessment of Liverpool's first-half performance at Palace as only Alisson Becker prevented an embarrassing half-time score.

However, Slot got little in the way of a response in another disjointed display from his array of star names.

Galatasaray had been thrashed 5-1 at Eintracht Frankfurt to start their Champions League campaign.

The Turkish champions are a far more formidable force on home soil, though, and made the most of Liverpool's defensive deficiencies.

Slot's decision to play midfielder Dominik Szoboszlai at right-back backfired.

Baris Alper Yilmaz gave the visitors a warning of the threat down Galatasaray's left when he failed to beat Alisson when one-on-one with the Brazilian.

Liverpool should have led just seconds before they fell behind.

Hugo Ekitike was denied by Ugurcan Cakir as he tried to round the goalkeeper and Ismail Jakobs cleared Cody Gakpo's follow-up effort off the line.

Galatasaray swiftly broke upfield and Yilmaz was awarded a soft penalty for a stray Szoboszlai arm into the Turkish international's face.

Osimhen had previously seen a Champions League penalty saved by Alisson, but this time converted the resulting spot-kick.

Florian Wirtz has struggled badly to deliver on his £100 million price tag and is still waiting for his first Liverpool goal after his effort was turned behind by Cakir, while Ibrahima Konate headed just off target from a corner before half-time.

Konate's poor form has been a major factor in the Reds' defensive issues at the start of the season and the Frenchman nearly cost his side a second goal early in the second half.

Alisson saved his teammate's blushes with another save from Osimhen but at a cost as the Liverpool number one suffered an injury sprinting off his line and had to be replaced by Giorgi Mamardashvili.

Slot introduced Salah and Isak on the hour mark, but Liverpool were still an impotent attacking force.

Isak fired tamely into the arms of Cakir with his first touch.

The closest the visitors came to a response was when French referee Clement Turpin intially pointed to the spot by a foul on Konate, but overturned his decision after a VAR review.

Instead it was Galatasaray who were inches away from the second goal of the night in stoppage time when Lucas Torreira drilled a shot just wide.