Inter coach Jose Mourinho lambasted his underperforming players after the Italian champions lost 1-0 at home to Panathinaikos on Wednesday night but still progressed to the Champions League last 16.
Inter have been inconsistent since Mourinho took over from the sacked Roberto Mancini in the close season with the opening 2-0 win at Panathinaikos in Group B, their only decent display in Europe this term.
"Panathinaikos's win is absolutely deserved. People may say they were lucky but I don't agree," Mourinho told reporters.
"After that performance we don't deserve to go through. We must be angry with ourselves."
Inter, who lead Serie A, still top the group and can make sure of first place with a win at Werder Bremen next month. However, their general performances have left some fans wondering why title winner Mancini was dismissed.
Saturday's 1-0 win over Juventus was Inter's best showing this term but they lacked tempo and creativity against the Greeks, who won thanks to Jose Sarriegi's second-half tap-in.
"After the joy of last Saturday, Inter fans have a sad moment and I am sorry. For what the players have done in previous seasons, they deserve some leniency from the fans," Mourinho added.
"We have qualified in the Champions League and are top of Serie A without luck so I hope the fans stay close to the team."
Substitute Ricardo Quaresma was booed by sections of the San Siro crowd in the second half having struggled since his big move from Porto.
"He did some positive things for the team... but it is not enough," Mourinho said of his Portuguese compatriot.
Asked if stuttering Inter could still win the Champions League, Mourinho said: "I think so. To succeed in this competition you have to be strong when it comes to the knock-out stages."
Memorable night
Panathinaikos midfielder Gilberto was understandably delighted with their surprise away defeat of Inter which kept the Greek club's European ambitions alive, lifting them into second place in Group B and within sight of the knock-out rounds.
"It's up to us now," said the Brazilian. "We just need to keep our heads."
Giorgos Karagounis also savoured Panathinaikos's win against the side he left three years ago, and whose supporters applauded him off when he was substituted in the second half.
"It was a memorable night, that's for sure," said the midfielder. "If the crowd here clap you off after all the great champions they've seen play here, it's wonderful for me.
"I don't think it was an unjust victory, it was fully deserved. We played without fear and achieved a great feat - it means so much to us."