Reeling from their Champions League exit in midweek, Inter dominated but were frustrated by a string of magnificent saves by Cagliari goalkeeper Alessio Cragno. Yet shortly before halftime the hosts were ahead against the run of play through Riccardo Sottil’s well-taken volley.
As frustrations grew, the Nerazzurri eventually found an equaliser courtesy of Barella’s thumping effort on his return to Sardinia, before substitute Danilo D’Ambrosio won it for Inter with his first touch. Deep into stoppage time Romelu Lukaku wrapped up victory as he ran the ball into an empty net.
Inter dominated the opening 15 minutes and had numerous opportunities to break the deadlock, only to find Cragno in inspired form. The Cagliari goalkeeper was on hand to keep out Lukaku in the box after the striker was in acres of space, and Christian Eriksen saw a follow up strike blocked.
Moments later Alessandro Bastoni blazed over on the volley after meeting a freekick, whilst Cragno got down low to keep Lukaku out again at the end of a rapid Inter counterattack, set up by a one-two between the Belgian and striker partner Alexis Sanchez.
It was then Sanchez’s turn to be left frustrated by the Cagliari custodian after he blocked a close-range header with his feet, as the Sardinians weathered an early onslaught.
Midway through the first half Cragno was again at full-stretch to keep Sanchez’s turn and shot out as Inter piled forward for an opener.
Yet the Nerazzurri were made to rue their missed chances, as Cagliari broke the deadlock shortly before the interval. A rare venture forward saw a lofted delivery teed into the path of Sottil by Leonardo Pavoletti, and after his initial strike was blocked by Stefan De Vrij, the winger caught the follow up on the volley to guide the ball into the far corner.
Cagliari ought to have doubled their advantage in stoppage time after another incisive breakaway, but Pavoletti was unable to turn Gabriele Zappa’s low cross in at the near post from close range.
The second half was a more dogged affair, though Inter again found Cragno in unstoppable form. On the hour mark Ashley Young latched onto Sanchez’s through ball and shot across the face of goal, but the Cagliari goalkeeper offered a strong hand to palm wide.
Sanchez saw a curling effort deflect wide and Milan Skriniar fired over in the box, but chances for the Nerazzurri were at a premium as Antonio Conte’s side struggled for rhythm.
At the other end, Joao Pedro launched a counter and met Alberto Cerri’s return pass on the edge of the box, but his tame shot was easily held.
Inter finally levelled with 15 minutes remaining through Barella’s magnificent strike, as he met a clearance from a corner with a vicious volley through a crowd.
Having clung on for much of the game, Cagliari were finally undone late on and it came via substitute D’Ambrosio’s first touch, with the full-back ghosting in at the back past from a corner to bundle the ball over the line.
With Cagliari pushing for an equaliser, Inter wrapped up the points deep in stoppage time. Cragno charged forward to attack a Cagliari corner and after the ball was cleared up field, Lukaku drove forward to fire into an empty net.