Two second-half goals hand the visitors a shock 2-1 win at Stadio Olimpico, and give the big-spending capital club and their new coach a far from ideal start to the season
The visitors, despite spending much of the match on the back foot, struck twice to give the Spanish boss a nightmare start in Serie A, with Daniele De Rossi's late goal proving no more than a consolation.
Roma had six Serie A debutants in the starting XI – Maarten Stekelenburg, Gabriel Heinze, Jose Angel, Miralem Pjanic, Bojan Krkic and Pablo Osvaldo – and the first half-hour was an incredibly cagey affair.
But the capital club did have a few decent chances; Jose Angel hit a piledriver on 15 minutes, forcing Cagliari keeper Michael Agazzi into a solid save.
Francesco Totti once again was at the heart of everything that Roma did well, winning possession, and attempting through balls. However, new signings Osvaldo and Bojan looked isolated as the wide men in a front three and were ineffectual throughout much of the half.
The second period, much like the first, started in a tight fashion, with much of the play congested around the centre of the pitch.
Roma were then hit with a sucker punch. Alessandro Agostini fired in a cross from the left-hand side, finding Conti who, against his old club, struck from 10 yards out to give Cagliari a 1-0 lead.
Things were to get even worse for the home side just two minutes later. Full-back Jose Angel lost the ball inside Cagliari's area and lashed out at Davide Astori, receiving a straight red card from the referee.
Fabio Borini correctly had a goal disallowed for offside with 10 minutes remaining, but other than that, Roma failed to put any pressure on the visitors in the dying moments. And with one minute remaining, El Kabir doubled Cagliari's lead, smashing the ball into the far corner.
De Rossi then made the scoreline slightly more respectable with the last kick of the game, pouncing on a loose ball in the box after a Totti free kick. But the damage was done, and Luis Enrique has been left with much to think about ahead of his side's next match.