Luciano Spalletti conceded that Roma were punished for an "ugly" performance in their 3-1 derby defeat to Lazio on Sunday.
Two goals from Balde Keita and a Dusan Basta strike secured the victory for Simone Inzaghi's side, with Daniele De Rossi's controversial penalty not enough for Roma.
The defeat leaves Roma nine points behind Juventus and all but ends their slip hopes of claiming the Serie A title.
Spalletti, who saw Antonio Rudiger sent off in the closing stages for a poor challenge on Filip Djordjevic, was disappointed with the display.
"Ugly incidents led to an ugly Roma," said the head coach. "We started well and we began playing the game we thought that we had to play and created several chances, and then we conceded with their first attempt.
"Naturally, that's a psychological blow. You start to think it's not the game you were expecting, you make mistakes and it becomes a wide-open game. We were no longer the team we know that we are."
The future of Spalletti beyond this season is likely to come under further scrutiny but Roma director Frederic Massara says no decision will be made yet.
"Spalletti is focused on finishing the season," he said. "He's done a great job, we have been close to an amazing team like Juventus. With Spalletti, we will see at the end of the season."
Roma's equaliser came in contentious circumstances, with Kevin Strootman earning a spot-kick after going to ground following a Wallace challenge that did not touch him.
Lazio boss Simone Inzaghi refused to criticise referee Daniele Orsato, however, and praised his side for their response.
"You can understand Orsato's mistake; I missed chances when I was a player," said the former striker.
"Along with [Nicola] Rizzoli, Orsato is the best referee in Italy. When I saw it during the break, I didn't think about the mistake but about motivating my players again.
"We had the right spirit and we very much deserved to win."