Inter trailed with 16 minutes remaining at Bologna, but Romelu Lukaku scored twice late on to send them back to the top of Serie A.
Romelu Lukaku was Inter's hero, converting an injury-time penalty for his second goal of the game as Antonio Conte's men came from behind to beat Bologna 2-1 at Stadio Renato Dall'Ara.
Despite enjoying the better of the first half, title-chasing Inter looked set to drop points when Roberto Soriano opened the scoring in the 59th minute, courtesy of a shot that took a deflection off Stefan de Vrij.
However, Lukaku pulled the Nerazzurri level with 15 minutes remaining, pouncing to convert a rebound from a tight angle.
And the striker held his nerve from the penalty spot to secure three points after strike partner Lautaro Martinez had been clumsily fouled by Riccardo Orsolini.
Bologna's players and coaching staff were left furious by the decision to award Inter a spot-kick, soon after former Inter forward Rodrigo Palacio had seen an appeal of his own turned down at the other end, but Inter will not care after they claimed their ninth win from 11 league games to reclaim top spot ahead of Juventus' clash with Torino.