Inter Milan's Turkish midfielder Hakan Çalhanoğlu scored the solitary goal that made all the difference in the key match against a resurgent Juventus on Sunday.
The win kept Inter's title defense alive and moved it three points behind leader AC Milan and Napoli, 3-1 winner at Atalanta.
The champion came away from the Allianz Stadium in Turin with a narrow win in a bad-tempered match decided by Çalhanoğlu's controversial spot-kick which was scored at the second attempt five minutes into first-half stoppage time.
Inter stays third with a game in hand and extends to four points the gap between itself and third-placed Juve, who will be 10 points off the pace with seven games remaining if Milan beats Bologna on Monday after its unbeaten league run ended at 16 matches.
"It's a huge step for us. We know that we've dropped points lately, but we're going to try to recover them over the remaining eight games," said coach Simone Inzaghi.
A game that started after an Italian and Ukrainian singer belted out a rendition of John Lennon's "Imagine" to promote peace in Ukraine turned ugly almost immediately after kick off, with rough tackles and niggly play which was dominated by the wasteful home side.
Events turned on the final few minutes of the opening period, with bedlam breaking out after Inter was awarded its spot-kick for Alvaro Morata treading on Denzel Dumfries' foot.
Çalhanoğlu's weak first effort was saved by Wojciech Szczesny and from there chaos ensued, with Inter's players celebrating after the ball was clumsily bundled in by Juve's defenders, only for that goal to be ruled out for a foul.
A check by the video assistant referee (VAR) then showed that Matthijs de Ligt, who stopped Çalhanoğlu from scoring on the rebound, had encroached in the area before the Turk missed his penalty, allowing him a second chance to slam home the opener which was taken with gusto.
Juve coach Massimiliano Allegri was livid on the sidelines but kept his cool post-match, saying that his team was "out of the title race" despite being the better team.
"I'm not going to say things that won't help right now," he said to DAZN.
"We played well and had lots of shots on goal, it's just a shame about the defeat."
The closest it came to scoring was through substitute Denis Zakaria's 72nd-minute shot which was tipped onto the post by Samir Handanovic but failed to create much more.
Napoli prevailed in Bergamo thanks to Lorenzo Insigne's early penalty, a sweet Matteo Politano volley eight minutes before halftime and a stunning late breakaway finished by Eljif Elmas just as Atalanta was pushing for a leveler after Marten De Roon pulled one back in the 59th minute.
Napoli was given a huge helping hand by captain Insigne, who was heavily criticized after Italy failed to reach a second World Cup in a row but opened the scoring and also laid on Politano's strike with a delicate free kick.
"We believe, we've always believed," said Insigne of Napoli's title hopes.
"There are still seven matches to go and they're seven big matches so we need to face them in the right way."
Defeat for Atalanta continued its dismal home record this season and leaves the one-time title hopeful in seventh, eight points behind fourth-placed Juve and with little realistic chance of a place in the Champions League.
De Roon's powerful header looked briefly to have given Atalanta hope of snatching a draw but instead, it fell to a fifth loss of the campaign at the Gewiss Stadium, where it has won only four league fixtures.
It has Fiorentina just a point behind following its 1-0 win over Tuscan rivals Empoli in Sunday's early match.
Three points ahead of Atalanta is Roma, in fifth after winning 1-0 at Sampdoria thanks to a beautifully-worked goal scored by Henrikh Mkhitaryan to extend an unbeaten league run to 10 matches.
Samp stays in 16th on 29 points, seven from the drop and four ahead of Cagliari, who was thumped 5-1 at Udinese thanks in part to a Beto hat trick.
