Ulster assistant coach Allen Clarke says the Irish province must "expect the unexpected" when they travel to France to face Oyonnax in Sunday's European Champions Cup Pool 1 game.

The Top 14 side have struggled for form this season and have lost their opening three group games in Europe but defeated Stade Francais in their last home game a fortnight ago, leading Clarke to describe them as a "conundrum".

"We have to focus on getting our own basics right, our systems, our attack and our defence, and we must back ourselves," said Clarke.