Simone Inzaghi questioned the attitude of his Lazio players against Serie A's top clubs after they were brushed aside by Inter on Monday.
Two goals from captain Mauro Icardi came either side of Marcelo Brozovic's 41st-minute strike at the Stadio Olimpico, the defeat ending a three-game winning run in all competitions.
Lazio's season has seen six victories in the league but they have been beaten by Juventus, Napoli, Roma and now Inter – four of Italy's top sides.
And that is a concern for Inzaghi, who has guided Lazio to successive fifth-placed finishes.
"We stayed in the game and created chances to score but cannot afford to concede the opening goal in that way," he told a media conference.
"After the first goal, we tried to react. We have to do better and I admit we deserved to lose.
"Against the big clubs, perhaps Lazio lack the conviction we have in other matches.
"It's also a matter of being up against a side that has Samir Handanovic in goal and Keita Balde Diao on the bench. These teams are built to win titles."
Lazio's task was made tougher with the first-half withdrawal of Milan Badelj, the midfielder having come in to replace the injured Lucas Leiva.
But Inzaghi refused to use the absence of two key players as an excuse for Lazio's reverse, insisting Inter proved they are "superior" to his side at present.
"Undoubtedly, that [Leiva's injury] is a big loss and Badelj added to it. Having said that, Inter are a superior team right now," Inzaghi added.
"Last season, we went to San Siro with real character and fought hard, while on May 20 we were superior until the final 20 minutes. Leiva's absence must not be used as an alibi."
