Andrea Petagna ignited a come-from-behind victory for struggling SPAL to hand his former club Atalanta a shock 2-1 defeat in Serie A on Monday.

The Champions League-chasing side from Bergamo had won their last two home games against AC Milan and Parma with 5-0 scorelines each time.

But they slipped up against SPAL who snatched just their fourth win of the season to move off the bottom of the table.

Gian Piero Gasperini’s team missed the chance to climb above Roma into the final Champions League place, and are now three points behind the side from the capital in fifth.

“Today more than a few players were not at their best,” said Gasperini. “It was clear we were down a gear.

“But we will have to be ready to immediately redeem a bad performance, because the standings are very tight.”

Slovenian forward Josip Ilicic put Atalanta ahead after 16 minutes with a clever back-heel flick beating Etrit Berisha in the SPAL goal.

But Petagna pulled SPAL level after 54 minutes by scoring his fifth goal in four meetings against his former club.

Mattia Valoti snatched the winner six minutes later with new signing Bryan Dabo playing a role in the goal on his first start for SPAL.

“I left a piece of heart in Bergamo because I started here,” said Petagna.

“But today we had to win, now we must continue like this if we want to save ourselves.”

Duvan Zapata missed chances to equalise for the hosts following a long injury layoff with fellow Colombian forward Luis Muriel coming on for the final half an hour in place of defender Mattia Caldara, who started on his return on loan from AC Milan.

But despite laying siege to the SPAL goal the hosts fell to their fifth defeat of the season and fourth at home.

“You have to give credit to SPAL, despite being last in the standings, they tried to play a decent game,” said Gasperini.

“Once in the lead, SPAL attacked with many men, but we weren’t good at fighting them.”

Gasperini’s side have the best attack in the league with 50 goals scored in 20 games.

But he had conceded that his players were suffering from fatigue after their surprise elimination from the Italian Cup by Fiorentina.

Atalanta are playing their first season in the Champions League and host Valencia in the last 16, first leg at San Siro on February 19.

Champions Juventus beat Parma 2-1 to open up a four-point advantage on second-placed Inter Milan who were held 1-1 at promoted Lecce on Sunday.

Lazio are third, a further two points behind with a game in hand, after hammering Sampdoria 5-1 on Saturday.