Florenzi was carried off in obvious pain after he landed awkwardly on his left foot and his left leg gave way.
Roma's seventh win of the campaign kept them in second place at just two points behind leaders and champions Juventus.
But the capital club's joy was tempered at full-time after seeing Florenzi, a highly-valued player for both Roma and Italy, carried off in obvious pain after he landed awkwardly on his left foot and his left leg gave way.
Roma's club doctor Lorenzo Del Vescovo said the initial prognosis seemed to rule out an anterior cruciate ligament injury -- for which the recovery time is around six months.
"We have two positive elements: the knee isn't swollen and our first tests on the cruciate ligament suggest it is stable," he told Sky Sport.
Del Vescovo said tests would be carried out immediately to rule out a "number of post-traumatic disorders" including a "fracture of the meniscus".
Losing Florenzi would be a considerable blow for Roma as they look to challenge Juventus for the scudetto, which the capital club has not won since 2001, in what could be club icon Francesco Totti's final season.
Coach Luciano Spalletti told Mediaset Premium: "He wouldn't let my hand go he was in so much pain.
"We're all sorry for him. It has eclipsed the joy of our win. We really didn't need an incident like that after such a great performance."