Bukayo Saka fired home just before half-time and scored the winner from the penalty spot, with Roberto Firmino equalising in between to have offered some hope.
It was Alexander-Arnold (4.6) who got the lowest rating, with the right-back again a shadow of his former self during his 45-minute appearance.
The 24-year-old’s defending left a lot to be desired and he was culpable for Saka’s goal that put Arsenal 2-1 up.
James Gray, of the i, bemoaned Alexander-Arnold’s “awful decision” to double up on Martinelli for the aforementioned goal, prior to being substituted.
TIA’s Henry Jackson felt he showed a “lack of intelligence” in his defensive work, as his much-criticised troubles continue.
The former was “all over the place for much of the opening quarter,” according to the Echo‘s Ian Doyle, and FotMob noted that he failed to win a tackle.
Meanwhile, Jackson said that “much more is required” from Salah, with his performances not close to the level they were at last season.
Next up was Virgil van Dijk (5.4), who produced another lethargic showing that played its part in Liverpool’s defeat.
Doyle claimed that the Dutchman was “conspicuously absent” for Saka’s first goal, with the Reds badly in need of his form improving.
Nunez (7.0) was the bright spark at the Emirates and the only Red to score above a 6, having found the net and looked a threat with his speed and movement.
Liverpool’s next assignment sees them make the trip to Rangers in the Champions League (8pm BST) on Wednesday evening.