Atalanta came from behind to beat second-place Napoli 2-1 on Monday, 22 April, and firmly put itself into contention for Serie A's last Champions League spot.
Adding another chapter to a career-best season, Duvan Zapata scored one goal and set up another to hand Napoli only its second home loss in the Italian league.
Atalanta moved level on points with AC Milan, which holds fourth place on head-to-head record.
The top four finishers enter the Champions League group phase.
Napoli remains second but is six points ahead of Inter Milan with five games remaining. Carlo Ancelotti's club has won only one of its last four Serie A matches and was eliminated by Arsenal in the Europa League quarterfinals last week.
Atalanta's 66 goals are second only to the 67 scored by Italian champion Juventus.
However, it took the visitors some time to find their aim following a first half marked by a heavy downpour at the San Paolo stadium.
Mario Pasalic scored the winner in the 80th with an angled shot after being set up by a back-heel pass from Zapata.
Zapata had equalised in the 69th by tapping in a cross after finally breaking free from center back Kalidou Koulibaly.
The former Napoli player's 21 goals ties AC Milan's Krzysztof Piatek for second in the league, one behind Fabio Quagliarella of Sampdoria.
Dries Mertens had given Napoli a first-half lead with a back-heel that deflected first off a defender and then his own backside before going in.
Napoli looked set to go 2-0 up when Arkadiusz Milik chipped over the goalkeeper, but Atalanta defender Andrea Masiello cleared the ball at the very last moment. Goal-line technology showed most of the ball – but not all of it – had crossed the line.
Lorenzo Insigne, who had very recently been considered Napoli's top striker, never left the bench amid a reported feud with Ancelotti.
Atalanta is also still in the Italian Cup semifinals, where it hosts Fiorentina in the second leg on Thursday following a 3-3 opening draw.
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