Having shipped four goals to a newly-promoted side for the first time since February 2012 last time out against Genoa, the hosts knew a positive response was needed against their in-form opponents.
Roma were lucky to avoid falling behind in the early stages when Marvin Cuni missed the target from a narrow angle, and Mourinho’s men punished the visitors just four minutes later through Lukaku.
Released in the box by a clever first-time pass from Paulo Dybala, the Belgian striker jinked his way past one defender before firing a clinical finish into the bottom corner.
Buoyed by the breakthrough, the Giallorossi looked to press home their advantage before the break, however, it was Frosinone who posed the greater threat in the final third.
For all their impressive play, wasteful finishing continued to prove costly for Eusebio Di Francesco’s side, as Cuni and Luca Mazzitelli failed to hit the target from promising positions, while Lukaku was denied a second at the other end by Stefano Turati.
Unbeaten in their last five league matches, the visitors were not ready to give up yet, and probed for an equaliser in the opening stages of the second half.
But Roma nearly doubled their lead on the hour mark, when Edoardo Bove saw a low strike thwarted by Turati. That save kept the scoreline tantalisingly poised heading into the final 20 minutes, as the hosts continued to search for an all-important second to take the game away from Frosinone.
Rasmus Kristensen came close to making an immediate impact from the bench when he directed a header into the grasp of Turati. However, there was to be no denying the hosts moments later, as Pellegrini finally made sure of the three points, tucking home at the back post from a superb Dybala delivery.
The result provides Roma with a morale-boosting victory, moving them up to 12th. As for Frosinone, their five-game unbeaten run comes to an end, but they’ll be satisfied with their return to the top-flight, sitting in the top-half after seven matches.
Flashscore Man of the Match: Paulo Dybala (Roma)
