Substitute Luis Muriel put Atalanta into the knockout stage of the Champions League on Wednesday, scoring in the 85th minute to secure a 1-0 win over 10-man Ajax and clinch second place in Group D.
As Ajax pressed forward in search of the victory it needed to progress, Remo Freuler won the ball in midfield and quickly passed to Muriel who rounded goalkeeper André Onana and slid the ball into the net.
Liverpool was already assured of top spot in Group D before it was held to a 1-1 draw at Midtjylland.
Atalanta progressed to the knockout stage of the Champions League for the second successive time, after reaching the quarterfinals last season on its debut in the competition.
Ajax finished third in the group and has to settle for a Europa League spot.
An injury-hit Ajax, missing Daley Blind, David Neres and Lassina Traore, had the best of the possession for most of the match but lacked attacking flair and could not break down the well-organized Atalanta defense.
It wasn't until stoppage time at the end of the first half that Ajax forced Atalanta's goalkeeper into action, with 18-year-old Brian Brobbey heading straight at Pierluigi Gollini after good work on the right flank by Antony.
Atalanta looked dangerous on the break but did not manage a shot on target in the opening half, with Netherlands international Marten de Roon's left foot effort high and wide in the 19th minute the most clear-cut chance.
They were more dangerous after the break, with Noussair Mazraoui blocking a shot by Matteo Pessina in the 66th as gaps opened in the Ajax defense.
Looking for more attacking options, Ajax coach Erik ten Hag brought on veteran striker Klaas Jan Huntelaar in place of defender Nicolás Tagliafico in the 63rd minute but it failed to produce a goal.
Midfielder Davy Klaassen squandered the best Ajax chance, shooting too close to Gollini, who saved well with an outstretched foot in the 75th minute.
Ajax was reduced to 10 men in the 79th minute when Ryan Gravenberch was sent off for his second yellow card after a foul on Alejandro Gómez.
