The visitors ensured a tense finish when back-row replacement Williams went over for a try O'Gara converted from the touchline.
BBC: Ospreys 19-14 Munster
2.
Back-row replacement Andy Powell proved his value as an impact player with some powerful running, but Toulouse continued to threaten as the minutes ticked away.
BBC: Cardiff Blues 9-6 Toulouse
3.
The blunt approach has been underlined by Gatland's candid responses to questions about dropping wing Mark Jones, centre Sonny Parker and back-row replacement Alix Popham.