Gian Piero Gasperini believes Atalanta secured the biggest win in their history by beating Liverpool at Anfield.
Second-half goals from Josip Ilicic and Robin Gosens earned the Serie A side a 2-0 triumph in their Champions League Group D clash on Wednesday evening.
Liverpool had won 5-0 in Italy earlier this month but their much-changed side failed to have a shot on target in the return clash.
And a delighted Gasperini said: “Obviously this is something which will be written in the pages of history.
“It is a shame there wasn't a crowd present, obviously this is a stadium that everyone is aware of its history, it is a part of the history of football.
“They haven't lost a Premier League game in 64 matches. This is perhaps our biggest ever victory in our history, certainly our most prestigious.
“These victories allow you to grow and develop and improve.”
Asked if the clean sheet was key to the victory, Gasperini responded: “Of course it is, you have to bear in mind we were more solid in defence this time around because the defence was better protected with more players in midfield.
“This is the solution we opted for as we thought it was appropriate for this game.”
Get all the latest Liverpool injury and team news as Klopp faces selection dilemma, plus breaking news and analysis of what's next for the Reds.
You'll also get the latest transfer talk and analysis straight to your inbox every day with our FREE email newsletter.
Sign up here - it only takes a few seconds!
Liverpool still top the group with nine points, although their lead has been cut to two by both Ajax and Atalanta.
The Italians will be hoping the Reds can do them a favour next week when Ajax visit Anfield, with Liverpool needing only a point to progress to the knockout stages.
Gasperini, though, believes Atalanta’s final group game at Ajax will determine the fate of his side.
“The next game's result is really important but the crucial game is going to be against Ajax in the final game,” he said.
“We're definitely in the Europa League, so that's a good thing and now it is for us to go as far as we can in the Champions League.”