If the Ospreys lose but pick up a bonus point they will miss out on a place in the European showpiece because it is impossible for them to have a superior points difference than the Blues in the event of a tie.
The Ospreys have the advantage of knowing exactly what is required which raises questions on why both games could not be played at the same time. Synchronised fixtures are taking place at the top of the table, at Llanelli and Leinster, so why not lower down?