Ivan Cordoba's late winner sent Internazionale back to the top of the table after basement side Reggina had threatened a shock comeback at the Stadio Oreste Granillo.
The visitors had established a two-goal lead with first-half strikes from Sisenado Maicon and Patrick Vieira.
But Reggina hit back with strikes from Francesco Cozza and Franco Brienza either side of half-time to heighten the prospect of an upset.
Cordoba, however, scored in stoppage time to spare Inter's blushes.
With their title rivals playing on Sunday, Inter moved to the top of Serie A with a one point advantage over Napoli and Udinese while Reggina remain rooted to the bottom of the table after recording their seventh defeat in 10 games this season.
Inter had dropped to fourth in the table after failing to win in their previous two outings and coach Jose Mourinho had still not forgiven Brazilian striker Adriano for ill-discipline that saw him dropped for Wednesday's goalless draw at Fiorentina.
But Ricardo Quaresma did return for Inter and Vieira was handed a start in the centre of midfield by Mourinho.
Mourinho's Reggina counterpart, Nevio Orlandi, also made changes with Bruno Cirillo returning to the defense after a ban with Francesco Cozza and Franco Brienza recalled.
But the changes caused only confusion for the Reggina defense early on with Zlatan Ibrahimovic and Maicon almost taking advantage of indecision and Andrea Campagnolo forced to pull off great save from the Brazilian's effort.
Brienza did have a long-range shot for Reggina in response but it sailed high over the bar and Inter grasped control of the game from then on and took the lead after nine minutes.
It was the productive combination of Ibrahimovic and Maicon that created the goal with the Brazilian firing Inter ahead.
Inter then doubled their advantage after 23 minutes. Quaresma played in Vieira who took the ball past Campagnolo and tapped into an empty net.
Despite being two down and under pressure, Reggina found a way back into the game after 34 minutes.
Cozza picked up the ball on the edge of the Nerazzurri penalty area and let fly a shot that went in the top corner of the net.
They could have had a second two minutes later but Brienza's shooting compass was still off.
Four minutes before half-time Inter had the ball in the net but Ibrahimovic's far-post header was ruled offside by the assistant referee.
Brienza then finally found his shooting accuracy and fired Reggina level from just inside the penalty area after 52 minutes
Despite Reggina pulling level, Inter continued to create chances and substitute Hernan Crespo failed to convert Quaresma's cross from close range.
Ibrahimovic missed a similarly inviting opportunity as Reggina's defense struggled to deal with the threat from the flanks.
Campagnolo, though, was in imposing form and he made a crucial stop with his feet from Mario Balotelli's cross shot.
With three minutes remaining Inter avoided an embarrassing defeat thanks to a one-handed Cesar save from Carlos Carmona's close-range effort.
And in the 91st minute Cordoba converted Balotelli's corner much to the relief of Inter fans.
