Lorenzo Pellegrini gave Roma a first-half lead at the Stadio Olimpico but Inter roared back after the break.
Milan Skriniar deservedly equalised with a header and Achraf Hakimi put Antonio Conte’s side in front seven minutes later.
Mancini stunned Inter four minutes from time, though, heading home to leave the Nerazzurri three points adrift of league leaders Milan.
Romelu Lukaku should have put Inter in front 12 minutes in, but Pau Lopez produced a magnificent reflex save to tip the fit-again striker’s close-range header over the crossbar.
— Lega Serie A (@SerieA_EN) January 10, 2021
It was the Giallorossi who took the lead five minutes later, Pellegrini clinically firing into the far corner from just outside the penalty area after Henrikh Mkhitaryan squared the ball into his path.
Samir Handanovic prevented Jordan Veretout from doubling Roma’s lead and although Lautaro Martinez found the back of the net, he had strayed offside during a first half that saw Ashley Young replace injured Inter wing-back Matteo Darmian.
Inter made a great start to the second period and Lopez brilliantly denied Martinez from point-blank range when Lukaku seemed to have put an equaliser on a plate for his strike partner.
There was nothing Lopez could do to stop Skriniar from levelling in the 56th minute, though, the defender rising to meet Marcelo Brozovic’s corner with a powerful header.
Roma were unable to contain the Nerazzurri and they were behind midway through the second half when Hakimi took a pass from Brozovic and beat Lopez with a superb left-footed strike that went in off the crossbar.
However, Inter were unable to hang on for three precious points, as they were caught out from a short corner that finished with Mancini diverting Gonazo Villar’s delivery beyond Handanovic.
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