Striker Nikica Jelavic knows Rangers must improve significantly if they are to overcome Maribor and reach the Europa League group stage.
The Ibrox side trail 2-1 after the first leg in Slovenia, having taken a first-half lead.
"We must win because the season is not the same without Europe," said the Croatian international.
"One goal will be enough but we will need to be better to win the game and it will be hard."
Juanma Ortiz's tap-in put the visitors in front on 31 minutes but second-half goals from Agim Ibraimi and Etien Velikonja gave the Maribor the advantage.
The away goal gives Rangers hope for next Thursday's return leg but the Slovenians looked sharp after the interval and will be dangerous opponents in Glasgow.
"I still think we are the better team," Jelavic told BBC Scotland.
"They really surprised me in the second half but we let them surprise us.
"The first half was much better but we stopped playing, like we were satisfied with 1-0.
"I don't know what happened and we need to analyse it before the second game and try to be better.
"I missed one or two chances but the way we lost they goals, that should not happen to Rangers.
"The manager was angry after the game and he was right to be."
Rangers boss Ally McCoist was disappointed to surrender a lead but took heart from the number of opportunities his team created in a bright opening 45 minutes.
"It was a very open game and I did feel we created a good number of goalscoring chances especially in the first half," he said.
"We didn't take as many as I would have liked but although disappointed I would have to say that I would still be very, very hopeful that we've got enough to win the tie and go through at home.
"We have to score and we will go out not just for one goal but for goals in the second game."