Back-to-back European Rugby Champions Cup winners Sarries kicked off their latest quest for silverware on the continent with a comfortable 57-13 victory on Sunday evening.
Wing Liam Williams crossed over twice as the visitors secured a four-try bonus point before the interval, leaving Mallinder under no illusion as to where the two teams currently stand on the European stage.
"They're a better side than us and we've got to be totally honest with that and put our hands up," BBC Sport quotes him as saying. "They've not lost in two and a half years in Europe and there's a reason for that.
"They're an exceptional side across the board. The game was over by half time and we've got to look at all those areas - set piece, first-up tackles, high balls. They've got quality all over the field and we've lost to a quality side, but it's not going to derail our season."
Northampton, who also lost George North to a knee injury, face last season's runners-up Clermont Auvergne in their next Pool Two outing.