Published Saturday, 08 September 2012
Mark Anscombe watched his side win in Swansea. (© Getty)
Mark Anscombe's side trailed by 10 points with 53 minutes on the clock at the Liberty Stadium - but two penalties from substitute Paddy Jackson closed the gap.
The visitors took the lead when Paul Marshall dived home with a try after a drive from John Afoa, which Jackson converted.
It was enough to give Ulster their second win of the new season following last week's 18-10 home victory over Glasgow at Ravenhill.
Replacements that included All Black prop John Afoa and Stephen Ferris made a major impact, turning the match on its head.
The arrival of Afoa and Ireland prop Tom Court saw the Ospreys scrum forced into retreat, while Ferris produced some thunderous tackles.
Another replacement, Paddy Jackson, nailed a couple of penalties to make it 13-9 before yet another member of the cavalry, scrum-half Paul Marshall, claimed the match-winning score with six minutes remaining.
A sharp counter-attack from wing Craig Gilroy set up the opportunity which eventually saw Marshall touch down from close range.
It needed the television match official to confirm the score, but Marshall and his Ulster team-mates were in little doubt.