Giuseppe Rossi celebrated his new contract with a goal in Fiorentina's straightforward win over Belenenses.
Scrappy first-half goals from Federico Bernardeschi and Khouma Babacar put Fiorentina on their way, before an own goal from Tonel and Rossi's late strike sealed a 4-0 victory in Europa League Group I.
Bernardeschi's goal was a rare flashpoint in a sluggish opening quarter, the Italy Under-21 international anticipating Matias Vecino's parried strike to slot in to an empty net.
Babacar's goal was similarly untidy, his left-foot shot from the edge of the area taking a heavy deflection off Belenenses centre-back Tonel, and it was the hapless Tonel who inadvertently turned in Jakub Blaszczykowski's low cross in the 83rd minute.
The injury-plagued Rossi, playing just his third European match in four years, showed none of the effects of his chronic knee problems, performing brightly before he tucked away Milan Badelj's delightful through ball.
Fiorentina looked the more comfortable of the sides from the opening stages, pegging Belenenses in their own half but still struggling to create a clear chance.
Indeed, it was the Portuguese side who created the first clear chance, Carlos Martins' whipped free-kick almost poked home by Luis Leal.
Belenenses were not in the ascendency for long, with Bernardeschi's tap in coming just moments later and forcing Ricardo Sa Pinto's side to sit even deeper.
Matias Fernandez was one of Fiorentina's few lively players, and it was his corner that was nearly flicked in for an own goal by Joao Afonso, the ball instead rebounding off the crossbar.
Coming just before half-time, Babacar's deflected strike could have finished the game as a contest, but Belenenses started strongly in the second half, Kuca fluffing a good chance after breezing into Fiorentina's penalty area.
However, it was not long before Belenenses, clearly under instruction to defend deep, faded once more.
Fernandez and Vecino never looked rushed as they controlled the midfield for Fiorentina, but Paulo Sousa's side failed to create another opening until Tonel's unfortunate third and Rossi's welcome fourth sealed the victory.