Fiorentina head coach Paulo Sousa has slammed his team's uninspired performance in the 2-1 defeat to Lech Poznan at Stadio Artemio Franchi on Thursday.
The Viola went behind in the second half to goals from Dawid Kownacki and Maciej Gajos, while Giuseppe Rossi's 90th-minute strike was not enough to take a point off the Polish side.
"We played with a slow tempo because our opponents today sat so deep with two very tight lines," Sousa told Sky Sport Italia, as the Tuscan side drop to the bottom of group I.
"Our lines at times were not in the right position to recover the ball. We had a great opportunity early on and if we'd scored, the spaces would've opened up and confidence would grow, but instead Poznan got more confident as the minutes ticked away.
"We should've taken our clear scoring opportunities, but we did not make the most of them. The movement of certain players wasn't great either, it was an issue of timing and this meant we couldn't find the spaces.
"Against very defensive sides like this you have to run a few more risks and go one-against-one, trying to shoot from distance if needs be. Our opponents sat so deep and our only option was to shoot from distance or the edge of the box."
Despite their struggles in the Europa League the Viola are top of the Serie A table, a position they will want to maintain when Roma, who are just one point behind in second, head to Florence on Sunday.