MILAN (AP) " Lazio won 3-1 at Roma in a controversial derby in Serie A on Sunday to leave its neighbors in the capital looking nervously over their shoulders.
Roma remained second, nine points behind Juventus with four rounds left, and third-place Napoli closed the gap to just one point.
"Ugly incidents led to an ugly Roma," Roma coach Luciano Spalletti said of his team. "We could have gone in front at the start, and they scored with their first chance. Then you allow too many counterattacks, make too many mistakes. You think it's not the match you had prepared ... we weren't the same team we usually are."
Fourth-place Lazio remained seven points behind Napoli after two goals from Keita Balde Diao and another from Dusan Basta handed it a first derby win in the league in nearly five years.
Roma had leveled through Daniele De Rossi's penalty after Wallace was harshly judged to have tripped Kevin Strootman.
Roma defender Antonio Rudiger was sent off in stoppage time for a dangerous challenge on Filip Djordjevic.
"We deserved it already from the first half, we had the right attitude from the start," Lazio captain Lucas Biglia said.
"(Lazio coach) Simone Inzaghi motivated the team and we couldn't not win it ... The referee acknowledged his error, everyone makes mistakes. I was really angry but then we continued to play our game."
Lazio made a late change before kickoff when Ciro Immobile pulled out ill during the warmup and was replaced by Jordan Lukaku.
Roma was out for revenge after losing the Italian Cup semifinal to its bitter rival and Lazio goalkeeper Thomas Strakosha was forced into early saves to deny Edin Dzeko and Mohamed Salah.
However, it was Lazio which took the lead with its first sight of goal in the 12th minute as Keita got away from Federico Fazio just inside the area and his shot went through Emerson Palmieri's legs and into the near bottom corner.
Keita almost turned provider in the 36th but Roma goalkeeper Wojciech Szczesny did well to tip Marco Parolo's effort around his post.
Lazio felt it should have had a penalty earlier when Fazio appeared to foul Lukaku but it was Roma that was awarded a spot kick just before halftime.
Televsion replays showed Wallace did not touch Strootman's ankle when the Netherlands midfielder went down in the area.
De Rossi stepped up and calmly sent the penalty into the bottom right corner.
Roma almost took the lead shortly after the break when Salah found Dzeko but Strakosha pulled off another great save.
Lazio restored its advantage three minutes later when Basta's strike from just outside the area was deflected past Szczesny by Fazio.
Basta hadn't scored in 79 Serie A games, since another goal against Roma for Udinese in March 2014.
Lazio looked the likelier to score again and did so five minutes from time. Senad Lulic sprinted down the left and into the area before rolling the ball across for an unmarked Keita to sidefoot home from close range.
INTER MILAN 0, NAPOLI 1
Napoli boosted its hopes of finishing second and gaining automatic entry into the Champions League thanks to a bad error by Inter Milan defender Yuto Nagatomo.
The team which finishes third has to go through a playoff for Europe's premier club competition.
Roma has a more difficult run-in than Napoli. It next faces AC Milan and Juventus before ending its season against Chievo Verona and Genoa. Napoli plays Cagliari, Torino, Fiorentina and Sampdoria.
Inter has picked up two points from its past six matches and slipped three points behind city rival AC Milan, which occupies the last qualifying spot for the Europa League
Napoli, which had earlier hit the post through Dries Mertens, took a deserved lead two minutes from halftime.
Nagatomo looked set to comfortably clear a cross but instead he hooked it over his head, leaving Jose Callejon to slot the ball between the near post and Inter goalkeeper Samir Handanovic.
AC Milan drew 1-1 at relegation-threatened Crotone as the new era at the famous Italian club continued without a win.
Milan has now drawn two matches and lost one since the $800 million takeover by Chinese-led Rossoneri Sport Luxembourg ended Silvio Berlusconi's 31-year reign.
Gabriel Paletta netted a scrappy goal for Milan early in the second half to cancel out Marcello Trotta's eighth minute opener.
Crotone moved to within four points of 17th-placed Empoli, which lost 3-1 at home to Sassuolo.
Palermo, in 19th place, also has hopes of avoiding relegation after beating Fiorentina 2-0.
Elsewhere, Chievo Verona came from behind to win 2-1 at Genoa, Bologna trounced Udinese 4-0 and Cagliari beat Pescara 1-0.
This story has been automatically published from the Associated Press wire which uses US spellings