Pasqual’s 14th-minute strike gave the visitors a lead they never surrendered in a fiery clash that saw eight players booked.
Genoa’s recent woes show no sign of ending however, as they slumped to their third successive defeat.
Luigi Del Neri has failed to deliver a point since taking charge of Genoa 11 days ago and will be champing at the bit to have star striker Marco Borriello back.
La Viola, however, broke their Ligurian curse with a first win at Genoa in 30 years and their fifth victory of the season has moved them to within one point of fourth-placed Lazio.
But they opened the scoring through an unlikely source in the 14th minute with their first attempt at goal.
Veteran left-back Pasqual had not scored since February 2011 but his exquisite lob from Gonzalo Rodriguez’s inch perfect pass left Genoa goalkeeper Sebastien Frey with no chance.
The hosts nearly hit back immediately afterwards through Juraj Kucka, whose shot from just outside the area was just too high while Mario Sampirisi forced a fine save from Emiliano Viviano.
Fiorentina were not content to sit on their lead and after the interval Frey was on hand to thwart Adem Ljajic’s goalbound effort.
At the other end Daniel Tozser was denied by Viviano while the Hungarian fired over in the closing stages as La Viola hung on.