Leonid Fedun, the owner of nine-time Russian champions Spartak Moscow, on Wednesday expressed bitter disappointment with his club's second consecutive defeat in the Champions League Group G.
"It's a nightmare and that's all I can say about this match and our position after it," Fedun said after Tuesday's 3-2 home defeat. "Everything went our way until that stupid sending off, which turned everything on its head."
Fedun, however, said that his side still had a chance to make it to the knockout stage and added that Spartak would battle until the very end to secure their qualification.
A last-minute goal by Giorgos Samaras gave the Scottish giants their first ever away win in 21 Champions League games, despite trailing 2-1 after an Emmanuel Emmenike brace.
The defeat came after the Russian club lost 3-2 against Barcelona in their first game.
Spartak's Dutch midfielder Demy De Zeeuw also blamed the sending off of Argentinian defender Juan Insaurralde for Tuesday's defeat.
"It's a terrible result," De Zeeuw said. "We've ruined the start allowing Celtic to score early but later in the first half we seized the initiative and got back on terms."
"We scored early in the second half and were in complete control but that stupid red card changed things drastically. But we have to admit that Celtic were also very good later on in the match."
De Zeeuw said Spartak have made their aim of making the knock-out stages more difficult and accepted that the Moscow club now had no other choice but to get maximum points in their matches against Portuguese outfit Benfica.
"Now we must beat Benfica twice," he said. "Otherwise I'm afraid the Champions League campaign will be finished for us."
Spartak's recently-signed midfielder Kim Kallstrom said the absence of captain and goalkeeper Andrei Dykan had a negative influence on the team but said his replacement Sergei Pesiakov was not to blame for the defeat.
"Pesiakov played well but we allowed Celtic to score three times," Kallstrom said. "But Andrei (Dykan) is our captain. He's very influential person and we missed him very much on Tuesday."