Badou Ndiaye, still contracted to Stoke, turned out for Galatasaray as they recorded a 3-0 victory over a Lokomotiv Moscow that featured Grzegorz Krychowiak, another player relegated last term.
"It is still so unbelievably hard".
Daniel Sturridge broke the deadlock in the 30th minute before James Milner doubled the home side's lead from the penalty spot to put Liverpool FC in command of the tie. But, it's early days and it's only one game so we're not going to get too excited.
Sturridge was making his first start of the season and his first in the Champions League for six years.
Sturridge was taken off to make way for Firmino, who was initially left on the bench by Klopp after suffering a nasty eye injury in a clash with Tottenham's Jan Vertonghen at Wembley on Saturday.
The Liverpool forward damaged his shoulder after he was hauled to the ground by Sergio Ramos during the first half in Kiev.
"The problem for Liverpool is the fans don't get up for the league games in the same way as they do in the Champions League", Barton told talkSPORT.
"The three in midfield also (were great) but they can only do that when the front three play like they do and in that number nine position he (Sturridge) did".
Jurgen Klopp has a near-full squad to choose from ahead of the game, but that could cause a headache for the German boss with so many players to slot into the starting XI.
Kylian Mbappe made the Reds pay for their wasteful in the second half with a late equaliser, but Roberto Firmino stepped off the bench to score a last-gasp victor. "The day before yesterday it was no chance", he said.
"Then bringing Bobby after 70 minutes, it's a nice tool to be honest, I really like that".