It appeared that Keita had injured his back or torso as the Liverpool medical staff attended him and he was subsequently stretchered off.
Keita "underwent a number of precautionary health checks" to assess his condition, according to the club's official website.
The 26-year-old was drinking with a group of friends outside a cafe on via Cesare Rosaroll in the city's historic centre just after midnight when they were accosted by a group of local men.
He said: "I heard it's a back problem, but we don't know exactly - we have to wait".
Ancelotti said, "The team did well throughout the game, we never lost control, were always very focused, above all when defending and allowed Liverpool practically nothing".
"No attempts on target, I don't remember when that happened last time", said Klopp.
Peace Puppies: Kim Jong Un Gifted Two Dogs to South Korea
In 2015, two South Korean soldiers were maimed by what Seoul said was a North Korean landmine, an accusation the North denied. This image depicts South and North Korean troops participating in a landmine removal operation in the Demilitarized Zone .
It was a deserved win for the home side, and one which blows Group C wide open with Napoli moving top on four points, one ahead of Paris Saint-Germain and Liverpool on three apiece.
"And you have seen it has been absolutely intense since the last worldwide break with the games we've had - twice Chelsea and stuff like that, coming to Napoli, playing PSG and now we have the game on Sunday against Man City".
"In the 89th minute we make another tactical mistake, we didn't close the gap between Joe (Gomez) and Virg (Virgil van Dijk), and then we can not react anymore".
"We had the chances to score earlier, but I think we timed it well".
"It would have been hard at any time in the season". Let's have a look how the players are after the game and then we will prepare.
"Then we have our crowd in the back". You were all full praise of our season and then tonight we didn't perform.
"But on Sunday that - at least - will be 100 per cent different".