Toulon picked up a crucial opening Heineken Cup win at home, after seeing off the Ospreys 19-14 in a scrappy contest in the south of France on Saturday.
A late try from England winger Paul Sackey earned Toulon victory.
Toulon had not produced a scoring opportunity in an attritional match before Sackey finally found some space on the left wing and scored with five minutes to play.
His finish will have pleased the watching England manager Martin Johnson, as will the fact that the try was set up by Jonny Wilkinson. As a neutral he will have enjoyed little else apart from the balmy weather, but a partisan Toulon crowd were sent home happy by their side's final flourish.
Toulon had produced virtually nothing of note up to that point and looked set to hand Ospreys a crucial away win in a group which includes London Irish and Munster.
As it is the Welsh side will have to settle for a losing bonus point as they begin their campaign for a third successive quarter-final berth.
The first hour was woeful. Toulon insisted on wasting possession and territory with a series of pick and drives which almost always ended - after a seeming eternity - with an Ospreys penalty for holding on.
Ospreys at least tried to get the ball out wide but without even hinting at a line-break.
Wilkinson and Dan Biggar exchanged three penalties apiece, with the Welshman kicking two from inside his own half.
The game finally came to life on the hour mark when Shane Williams scored from nowhere with a typical piece of opportunism.
When play broke down around the Toulon 22, the veteran Wales winger spotted that Sackey had been sucked into the tackle area and darted round the blindside of the ruck to race in almost unopposed.
Biggar missed the conversion and a subsequent penalty and that cost the visitors dear.
Toulon finally gave up on their forward drives with five minutes to play, Wilkinson running laterally and exhanging passes in midfield before firing out a long pass to Sackey.
The winger's pace did the rest and Wilkinson converted from the touchline to complete the victory.
For Toulon:Try: Sackey
Cons: Wilkinson Pens: Wilkinson 4
Pens: Biggar 3
Toulon: 15 Rory Lamont, 14 Paul Sackey, 13 Mafi Kefu, 12 Geoffroy Messina, 11 Benjamin Lapeyre, 10 Jonny Wilkinson, 9 Matt Henjak, 8 Juan Fernandez Lobbe, 7 George Smith, 6 Olivier Missoup, 5 Christophe Samson, 4 Dean Schofield, 3 Davit Kubriashvili, 2 Jean-Charles Orioli,1 Saimone Taumoepeau
Replacements: 16 Mickael Ivaldi, 17 Benjamin Basteres, 18 Mehdi Merabet, 19 Thomas Sourice, 20 Tom May, 21 Clement Marienval, 22 Laurent Magnaval, 23 Jocelino Suta.
Ospreys: 15 Lee Byrne, 14 Tommy Bowe, 13 Andrew Bishop, 12 James Hook, 11 Shane Williams, 10 Dan Biggar, 9 Mike Phillips, 8 Jonathan Thomas, 7 Marty Holah, 6 Jerry Collins, 5 Alun Wyn Jones (C), 4 Ian Gough, 3 Adam Jones, 2 Richard Hibbard, 1 Paul James
Replacements:16 Huw Bennett, 17 Ryan Bevington, 18 Craig Mitchell, 19 Ryan Jones, 20 Justin Tipuric, 21 Jamie Nutbrown, 22 Gareth Owen, 23 Nikki Walker
Referee: Alan Lewis