Juventus were 2-0 up and coasting at Milan on Tuesday before collapsing in utterly abject fashion.
Three goals in five minutes turned the game on its head before Ante Rebic completed a 4-2 triumph for the Rossoneri.
A seven-point lead with seven games remaining means Maurizio Sarri's men remain on course for the Scudetto.
But up next are fourth-placed Atalanta, themselves nine points from the summit. After their San Siro ordeal, a showdown with one of the most exciting and dangerous teams in European football might be the last thing Juve need.
PERFECT SINCE LOCKDOWN
Saturday's match at the Allianz Stadium brings together two attacking ideologues. Sarri's high-pressing, high-possession approach became so ingrained during his celebrated spell at Napoli that it was given its own nickname.
But Sarrismo has a more than worthy adversary in Gian Piero Gasperini's thrilling, fearless setup.
Atalanta's expansive 3-4-1-2 system, in which central midfielders, wing-backs and forwards freely exchange positions to repeatedly overload opponents in wide areas, has produced goals by the truckload this season.
They head to Turin in prime form, buoyed by a run of nine Serie A wins in succession – the club's longest ever such tally in the top flight.
Along with Bayern Munich and Real Madrid – both potential Champions League final opponents in these heady days for Atalanta – they are one of three teams in Europe's top five leagues to have won all their games since lockdown.
Overall, La Dea have 20 victories this term, which is one shy of the single season record Gasperini set during his first campaign at the helm in 2016-17.
GOALS, GOALS, GOALS
While Gasperini's masterpiece is one of collective ingenuity, there are also some very impressive individual numbers.
If Duvan Zapata manages one more league goal, Atalanta will be the first side to have three players with 15 or more to their name in a Serie A season since Juventus in 1951-52, when Ermes Muccinelli, Giampiero Boniperti and John Hansen accomplished the feat
Luis Muriel and Josip Ilicic have 17 and 15 respectively, with Muriel's feat all the more impressive when considering he typically begins matches on the bench.
Indeed, the Colombia international is only the second player to score double figures in a single season via substitute appearances across the top five leagues, after Paco Alcacer did likewise at Borussia Dortmund in 2018-19.
The dazzling firecracker at the creative centre of this explosive attack is Alejandro 'Papu' Gomez, who is set to make his 300th Serie A appearance against Juventus.
The 32-year-old Argentinian playmaker enjoys free rein as Gasperini's number 10 and has racked up 15 assists this term – the highest single-season figure since Opta started collecting such data in 2004-05.
Gomez has provided at least 10 Serie A assists in each of his four seasons under Gasperini and the former Catania man has 128 goal involvements in Italy's top flight overall (61 goals and 67 assists).
GATECRASHING EUROPE'S ELITE
A rampaging last-16 win over Valencia booked Atalanta's place in the Champions League quarter-finals, where they will take on Paris Saint-Germain when Europe's elite club competition lands in Lisbon for its concluding mini-tournament next month.
Their performances truly are among the very best on the continent
Only Bayern (100) and Manchester City (86) have scored more league goals than Atalanta's 85 in 2019-20.
That amounts to an average of 2.74 per game, again the third best in Europe. Dominant Bundesliga winners Bayern edged up to 2.94 per game, while PSG averaged 2.78 across the truncated Ligue 1 season.
Along with City and Barcelona, Atalanta have scored five or more goals in five separate matches. That can only be bettered in the Bundesliga, where Bayern and Dortmund each did it six times.
Things are also looking pleasingly tight at the back. In 2020, La Dea have five Serie A clean sheets, edged in the calendar year so far by Juventus and Milan with six apiece.
Juve certainly should not bank on adding to that number when they host Gasperini's great entertainers. If Atalanta manage to storm Turin, it will be 10 wins in a row and the gap will be six points with six games to play.
They can't... can they?