Mauro Icardi's second-half goal spared Inter Milan from embarrassment against 10-man Frosinone.
The Argentinian struck the only goal of a 1-0 Nerazzurri victory at the Stadio Matusa before Frosinone's Leonardo Blanchard was dismissed for picking up a second yellow card.
The win gives Inter a fighting chance of snatching the final Champions League place from in-form Roma, who are five points better off ahead of their Monday night meeting with Bologna.
Last year's Serie B runners-up Frosinone remain a point shy of safety and could be cut adrift in the drop zone if Palermo and Carpi secure positive results over the weekend.
Roberto Mancini's men dominated the first half with rare starter Jonathan Biabiany going close and setting up Ivan Perisic for a shot past the far post shortly before half-time.
Inter's frustration in front of goal continued after the break - Jeison Murillo, Stevan Jovetic and Perisic all wasted opportunities from good positions - while Frosinone hit a post through Luca Paganini.
In the 74th minute the Nerazzurri made an overdue breakthrough. Perisic's cross beat the entire home defence and met Icardi's head, allowing him to register his 13th goal of the season.
Frosinone's hopes of fighting back suffered a blow 10 minutes from time as centre-back Blanchard, already sanctioned for a foul on Icardi, saw red following his late challenge on Jovetic.
Inter could have rubber-stamped the win in stoppage time but Perisic somehow managed to miss the target when it would have been easier to score.