Roma boss Jose Mourinho was left disappointed following their shock 3-2 loss at Hellas Verona.
Pellegrini gave Roma the lead, but they later collapsed against a Verona which had only just replaced coach Eusebio di Francesco with Igor Tudor.
“I knew that Verona had a lot of quality and that they were difficult to play against, especially that after a change of coach there is usually a psychological reaction, which is what we saw today,” Mourinho told DAZN.
“Tudor’s style of football is very similar to the one Hellas played last season under Ivan Juric, so it wasn’t hard for the players to adapt to him.
“We put the effort in, I cannot complain about that, but we lost too many individual duels. Hellas had more intensity. Now I need a few hours in front of the video replays to work out what just happened.”
He added: “We didn’t interpret the situations properly. Nicolò Zaniolo was meant to drop deeper and protect Rick Karsdorp, not press forward. We also went too heavy on the long ball.”