Italian champions Napoli came unstuck at Bologna on Sunday, losing 2-0 to cede the Serie A summit to Roma, who beat Udinese by the same scoreline.
Goals in the capital, either side of the break, by Lorenzo Pellegrini and Zeki Celik sent Gian Piero Gasperini's side to the top of the table on 24 points after 11 outings.
The breakthrough came for Roma when Hassane Kamara conceded a penalty after handling in the Udinese box.
Pellegrini stepped up in the 42nd minute to send Maduka Okoye the wrong way.
The Romans wrapped up the vital three points one minute after the hour as Celik forced home from Gianluca Mancini's cut-back.
Udinese had chances to get themselves back into the match inside the final 20 minutes but Roma goalkeeper Mile Svilar stood strong to deny first Nicolo Zaniolo, then Vakoun Issouf Bayo.
Earlier, Napoli failed to take advantage of AC Milan's collapse against Parma on Saturday when they were held 2-2 after leading by two goals as they went down at the Stadio Renato Dall'Ara.
After a goalless first half, Napoli were caught off-guard five minutes after the break by a precise shot by Thijs Dallinga following a magnificent cross from the left by Nicolo Cambiaghi.
In the 66th minute, Bologna wrapped up the win. This time the danger came from the right: a cross and a header by Jhon Lucumi into Napoli's top right corner.
Bologna moved to fifth, a point off Napoli.
Inter Milan, three points behind Roma, can finish Sunday as Serie A leaders if they win their game against Lazio due to their superior goal difference.
In other action, Sassuolo downed Atalanta 3-0 and struggling Genoa were held 2-2 by last-placed Fiorentina.
