Atalanta coach Gian Piero Gasperini hailed a performance his club will "remember forever" after the Italian side crushed Valencia 4-1 on Wednesday to take a giant step closer to reaching the Champions League quarter-finals for the first time, reports AFP.
Dutch wing-back Hans Hateboer scored twice on 16 and 62 minutes, sandwiching goals from Josip Ilicic and Remo Freuler.
"This is an evening that we'll remember forever," said Gasperini. "It's an amazing result, full of emotion."
It was an extraordinary night for the side from Bergamo who travelled to the San Siro with over 40,000 of their fans as their home stadium 55km away does not meet UEFA regulations.
Denis Cheryshev pulled one back for Valencia in the first leg of the last-16 tie at the San Siro, the same stadium where the Spanish side lost the 2001 final to Bayern Munich on penalties.
Valencia, seventh in La Liga, had finished top of their group after away wins over Ajax and Chelsea but were missing several key players through injury and suspension.
"It certainly complicates things a bit, it's a pretty overwhelming result, this 4-1," said Valencia coach Albert Celades.
"In the end it doesn't reflect much what we saw on the pitch."
Atalanta's run comes despite losing their opening three Champions League group games, before finishing second behind Manchester City.
"Three goals ahead is a nice reward," added Gasperini. "But there were a lot of dangerous situations, these are things we'll need to improve in Valencia.
"We are satisfied with this victory and above all with this advantage.
"Yesterday I would have signed to go to Valencia in the return game with a three-goal lead."
