Atalanta striker Giacomo Bonaventura scored a brace in a 2-1 away win which pushed Inter Milan down to sixth in Serie A on Sunday as Verona's Europa League hopes were dented by a 5-0 rout away to Sampdoria.
Inter hosted the Bergamo-based side looking to stretch their unbeaten run to seven games and tighten their grip on fifth place.
However despite Mauro Icardi levelling for the hosts only a minute after Bonaventura had given Atalanta a 35th minute lead, Walter Mazzarri's side spurned a series of chances to put the match beyond reach in a lively second half.
Inter's first defeat since a 3-1 reverse to Juventus in early February means they drop to sixth, with Parma, who also have 47 points but a game in hand, moving up to fifth despite a 1-1 draw at home earlier by Genoa.
Atalanta's 12th win of the campaign moved them up to eighth, one place ahead of crisis-hit Verona.
Having missed out on Europe this season, Inter are desperate not to miss the boat but a jaded-looking Mazzarri admitted his side's setbacks could prove costly.
"A team like Atalanta have nothing to lose by coming here and playing well. We knew they'd be a dangerous side but we had a great second half," said Mazzarri.
"We had at least three chances to score but we just couldn't put the ball in the back of the net. It's a strange season. We're making too many mistakes, and they could be costly."
At the turn of the year Andrea Mandorlini's Verona were firmly in contention for a top five finish and a place in the Europa League.
However the visitors were playing catch-up from the off following Gianluca Sansone's fourth-minute strike and after Luca Toni missed a great chance to level from close range Sampdoria doubled their lead, albeit with a little help from the referee.
A corner in the 23rd minute deflected off the match official and into the path of Renan, who beat Rafael low at the 'keeper's near post.
Samp took a 3-0 half-time lead thanks to Roberto Soriano's close range strike and he completed his brace thanks to a fine individual effort on 48 minutes.
Angelo Palombo hit Samp's fifth just before the hour to complete the rout and move Sinisa Mihajlovic's men up to 11th place.
In a veiled reference to William Shakespeare's Verona-based lovers Romeo and Juliet, Mihajlovic quipped: "We've thrown Juliet from the balcony. But she's not too hurt. They (Verona) still have 40 points.
"Mathematically, we're not safe from relegation but virtually we are."
Elsewhere, Antonio Di Natale secured a 1-0 win for Udinese over struggling Sassuolo with a diving header at the back post after Giampiero Pinzi's shot had been charged down in the box.
Minutes later the referee pointed to the penalty spot when Di Natale's freekick hit the shoulder of Diego Farias as he jumped to defend in the wall.
Justice appeared done when veteran striker Di Natale skied his effort over the crossbar.
Leaders Juventus visit basement side Catania later Sunday looking to restore their 14-point lead over second-placed Roma, who like Parma have a game in hand, after the side from the capital reduced arrears thanks to a 2-0 win at Chievo on Saturday.
Napoli, who sit third six points behind Roma, host Fiorentina while struggling Milan, who now sit 13th and still 40 points adrift of Juve, are away to Lazio.