It has been difficult so far for Los Che, who have already fired Mauricio Pellegrino after a poor start to the season.
“It’s very important because we’ve had four consecutive years in the top four and it’s almost like an obligation,” Viera told UEFA.
“It’s very complicated because our rivals are very strong, but we have to be there, both from a sporting and economic perspective.
“I think in the Champions League things have gone well, except the first match against Bayern Munich, but we learnt from that.
“At home in the League we have done well, but away it has been more difficult. It’s more of a psychological thing.”