But, with another crucial game at Aberdeen in the SPL looming on Saturday, Papac knows Rangers must put their European disappointment firmly in the past.
"We must focus on the SPL now," he said.
"The Champions League is over now and we can forget it for this year. We lost the game against Stuttgart but the next time we can win.
"Losing is part of football. I lost the UEFA Cup final and continued to play football so now is no problem after losing a Champions League game.
"You are always up against good teams in the Champions League and, this year, we only took two points so we have to forget it now.
"We were terrible in the home games and I don't know why. We were under pressure and we didn't play well. We played much better away this season in the Champions League."
Rangers may have the better pedigree in Europe but they found themselves out-classed by little-heard of Romanian outfit Unirea Urziceni, who are still on track to qualify for the last 16 of the Champions League.
But Papac insisted: "We must look at this team next season or what they were like two or three season before.
"Unirea is not a team for a long period. This year something has happened and I'm not sure this can continue next year or for two or three years. Unirea have given the maximum this year.
"If you want to play in the Champions League for many years, you must always put money into football.
"We have more quality than Unirea but we haven't played well in the Champions League this season, especially at home."
Papac admits the problems dogging Scottish football as a whole this season come down to one thing.
"We can always speak about money and money is important in football now," he said.
"If you buy a good player here in Scotland, everyone in Scotland can learn from that good player. But, in the last two or three years, I don't see a big transfer here."
Meanwhile, Papac claims he has no problem with Madjid Bougherra after the defender was criticised by some of his club-mates for failing to return on time from international duty with Algeria for the third time this season last weekend.
"I have no problem," he said.
"If there is a problem, Madjid must speak with the gaffer about this and not with me."
Rangers 4/5, Draw 13/5, Aberdeen 10/3