Ospreys clinch a bonus-point 37-7 win over Connacht at the Liberty Stadium on Saturday - a result that leaves the Irish anchored to the bottom of the table.
Wales scrum-half Mike Phillips, included after he was released for the match by the Wales management, scored one of his side's four tries as the Ospreys registered a bonus-point Magners League victory over Connacht at the Liberty Stadium.
It took only three minutes for the hosts to get on the scoreboard through a Shaun Connor penalty. That lead was extended with a second three-pointer after Marshall was high-tackled by Robbie Morris.
By contrast Andrew Dunne was wayward with two penalty attempts after nine and 11 minutes for Connacht.
Connor got the home side into a good position with a penalty kick to the corner and from the resulting line-out Paul James went in at the right corner, but the try was ruled out by the video referee.
Connacht did not get any change out of a solid Ospreys defence and the Welsh region grabbed two injury-time tries to change the complexion of the game in the space of five minutes.
First Nikki Walker broke through midfield and ran in unopposed from 40 metres out for Connor to convert.
And just before half-time Marty Holah went over under the posts following a battering run from Filo Tiatia from a scrum on the 22.
It gave the Ospreys a 20-0 cushion at the interval.
That lead was extended to 23 points when Connor converted his third penalty five minutes into the second half just before replacement flanker Colm Rigney was sin-binned for persistently offending at the ruck.
Phillips rounded off a satisfying evening's work with a try that he ran in from 20 metres out after scooping up a loose ball, before replacement fly-half Gareth Owen went in for his first try for the Ospreys resulting in a bonus-point in the final minute.
In injury time former Ireland flanker Jonny O'Connor put Connacht on the scoreboard with a converted try.
The scorers:
For Ospreys:
Tries: Walker, Holah, Phillips, Owen
Cons: Connor 2, Owen 2
Pens: Connor 3
For Connacht:
Try: O'Connor
Con: Donnelly
Ospreys: 15 Justin Marshall, 14 Johnny Vaughton, 13 Mark Taylor, 12 Jonathan Spratt, 11 Nikki Walker, 10 Shaun Connor, 9 Mike Phillips, 8 Filo Tiatia (c), 7 Marty Holah, 6 Ben Lewis, 5 Lyndon Bateman, 4 Andy Lloyd, 3 Cai Griffiths, 2 Richard Hibbard, 1 Paul James
Replacements: 16 Ed Shervington, 17 Andrew Millward, 18 Mike Powell, 19 Tom Smith, 20 Martin Roberts, 21 Gareth Owen, 22 Aled Brew.
Connacht: 15 Gavin Duffy, 14 D Riordan, 13 Matt Mostyn, 12 Mel Deane, 11 Aidan Wynne, 10 Andy Dunne, 9 Conor McPhillips, 8 John Muldoon, 7 Jonny O'Connor, 6 Mike McCarthy, 5 Andrew Farley (c),4 Michael Swift, 3 Robbie Morris, 2 Adrian Flavin, 1 Brett Wilkinson
Replacements: 16 John Fogarty, 17 Ronan Loughney, 18 David Gannon, 19 Ray Ofisa, 20 Colm Rigney, 21 Conor O'Loughlin, 22 Tim Donnelly.
Referee: Andy MacPherson (Scotland)
Touch judges: Matthew Aplin (Wales), Colin Kirkhouse (Wales)
Television match official: Tony Rowlands (Wales)