The Ospreys went top of the Magners League despite an unconvincing performance, beating basement-dwelling Connacht 19-17 at the Liberty Stadium in Swansea on Sunday.
But the Welsh region were buoyed by the return of Lions scrum-half Mike Phillips. He came on at half-time for his first rugby since tearing ankle ligaments last October.
Dan Biggar, released for the match by the Wales squad, provided 14 points with a try and three penalties as the Ospreys just squeezed home.
Biggar found himself in the thick of the early action. First he missed a drop goal before being successful with a 45-metre penalty.
And then the 20-year-old was on hand to drag down Connacht hooker Sean Cronin to prevent a certain try.
Connacht drew level on 14 minutes with an Ian Keatley penalty.
Biggar then missed an easy penalty shot but from the restart the Ospreys scored a spectacular try. Full-back Gareth Owen ran in with real pace going through two men and then rounded the full-back as the home side led 8-3 after 19 minutes.
After a Connacht try was ruled out by the TV match official, despite number eight George Naoupu believing he had grounded the ball, the lively Irishmen breached the Ospreys' 22 only for Owen to pull off a fine tackle on scrum-half Connor O'Loughlin.
Connacht's endeavours were finally rewarded with a second penalty for Ian Keatley to reduce the Ospreys lead to 8-6 on 35 minutes.
In first-half injury time a flowing Ospreys attack ended with the award of a penalty which Biggar converted from the 22 to give his side an 11-6 interval lead.
Phillips emerged at half-time to a warm welcome from the home faithful and almost immediately the Ospreys opened up a 13-point lead with a penalty and try for Biggar within the first nine minutes of the restart.
Biggar went in at the left corner after receiving a reverse pass from Owen.
But any hopes of then going for the bonus point win had to be delayed after second row Ian Evans was yellow-carded for a high tackle, and with the extra man Connacht grabbed a try through hooker Sean Cronin.
And 19-11 became 19-14 as Keatley converted a penalty from in front of the posts.
In injury time, despite being down a man due to Gavin Duffy's sin-binning, Connacht then cut the deficit to just two points with Keatley's fourth penalty.
Tries: Owen, Biggar
Pens: Biggar 3
Pens: Keatley 4
Ospreys: 15 Gareth Owen, 14 Jonny Vaughton, 13 Sonny Parker, 12 Ashley Beck, 11 Nikki Walker, 10 Dan Biggar, 9 Jamie Nutbrown, 8 Filo Tiatia, 7 Marty Holah, 6 Tom Smith, 5 Ian Evans, 4 Ian Gough (c), 3 Craig Mitchell, 2 Richard Hibbard, 1 Ryan Bevington.
Replacements: 16 Ed Shervington, 17 Cai Griffiths, 18 Andy Lloyd, 19 Jerry Collins, 20 Mike Phillips, 21 Barry Davies, 22 Tom Prydie.
Connacht: 15 Gavin Duffy, 14 Troy Nathan, 13 Niva Ta'auso, 12 Keith Mathews, 11 Fionn Carr, 10 Ian Keatley, 9 Frank Murphy, 8 George Naoupu, 7 Ray Ofisa, 6 John Muldoon, 5 Bernie Upton, 4 Michael Swift, 3 Robbie Morris, 2 Sean Cronin, 1 Brett Wilkinson.
Replacements: 16 Adrian Flavin, 17 Jamie Hagan, 18 Mike McCarthy, 19 Johnny O'Connor, 20 Conor O'Loughlin, 21 Adian Wynne, 22 Liam Bibo.
Referee: Neil Paterson (Scotland)