The Ospreys beat Connacht 24-20 but could not record a bonus point for a home PRO12 play-off.
Connacht their hopes of European Champions Cup qualification alive with a 40-10 bonus point win over Zebre.
With one round remaining and the top four sides split by a point there is still everything to play for in the PRO12.
Stuart Barnes says that players should not be banned for accidental acts after Iain Henderson was red-carded for Ulster.
Zebre skipper Mauro Bergamasco will make his final home appearance when they host Connacht on Saturday.
Watch all the highlights of this weekend's Guinness PRO12 action.
Glasgow Warriors' clinical finishing proved too much for Connacht as they ran out 31-13 bonus-point winners in Galway.
Connacht have made three changes in preparation for their Guinness PRO12 game against league leaders Glasgow.
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