David Strettle sees a surgeon today for an assessment on the left foot he injured playing for Harlequins in the Guinness Premiership match against Worcester Warriors on Thursday. If the England wing needed a fillip, though, he received it from his team-mates at the Liberty Stadium yesterday.

It would be easy to mistake the Ospreys, the cup holders, for Wales - certainly four of the national team's management were watching - while Harlequins had only one survivor from Thursday's starting XV (Chris Robshaw) in their side. Yet it took an injury-time conversion by James Hook to edge the Ospreys ahead and ensure that all four Welsh regions opened this tournament victorious.

Therefore, Harlequins could take enormous encouragement from a courageous and skilful second-half display, which will offset the possibility of bad news once Strettle has had a scan. There are fears that he has broken a small bone in the same foot that has suffered two metatarsal injuries in the past year and that he could be out for up to ten weeks, which would remove him from contention for the November internationals.

However, it will have done wonders for the confidence of players such as Charlie Amesbury, James Percival and Mark Lambert to have gone head to head with so strong a team as the Ospreys and come within a couple of minutes of winning. “We don't have a second team as such, we have a lot of ability across the board,” Dean Richards, the Harlequins director of rugby, said. “A game like that teaches our young guys not to show opponents too much respect - which I feel we did in the first half - to get stuck in and play what they see.”

The Ospreys, who are second in the Magners League, play Leicester in the Heineken Cup on Sunday, a match that may have been on their minds, and even good players need a reminder of a few home truths. But they will be concerned that they could not stop the Harlequins forwards making ground with a close-passing game and that their illustrious backs, of whom Sonny Parker may have damaged a chest muscle, could not break the advantage line more frequently.

Hook helped them to a 9-3 advantage with three penalty goals and when Alun-Wyn Jones opened up the field, he lobbed a pass to Gavin Henson, who was playing his first 80 minutes this season, and Shane Williams was on hand to finish. Harlequins lost Epi Taione to the sin-bin either side of half-time, but before his return they had worked De Wet Barry over from a pass by the persevering Tosh Masson.

Barry, the former South Africa centre, was involved again with Waisea Luveniyali before Tani Fuga squeezed over at the bottom of a heap of bodies and suddenly there was a ripple of concern in the Ospreys ranks. Worse, Ryan Jones, their captain, left for the sin-bin for slowing down possession at a ruck and Luveniyali, so erratic as a goalkicker less than a month ago, kicked two penalty goals to help his team to a 23-17 lead.

Tom Williams did well to cover a grub-kick through by Shane Williams but then blotted his copybook by throwing the ball away to deny Ospreys a quick lineout. Yet Hook missed the penalty and Lambert almost set up Barry for another try by intercepting Lee Byrne's underhit chip-kick.

But Byrne helped the Ospreys to the last word. He prodded a kick through and although Amesbury appeared to have retrieved possession five metres from his line, the ball bobbled away from him into the path of Tommy Bowe, the Ireland wing touching down before Hook's conversion was greeted by an exhalation of local relief.

Scorers: Ospreys: Tries: S Williams (39min), Bowe (80+3). Conversion: Hook. Penalty goals: Hook 4 (13, 26, 37, 66). Harlequins: Tries: Barry (44), Fuga (56). Conversions: Luveniyali 2. Penalty goals: Luveniyali 3 (32, 63, 67).

Scoring sequence (Ospreys first): 3-0, 6-0, 6-3, 9-3, 14-3 (half-time), 14-10, 14-17, 14-20, 17-20, 17-23, 24-23.

Ospreys: L Byrne; J Vaughton, S Parker (rep: TBowe, 41), G Henson, S Williams; J Hook, R Webb (rep: D Biggar, 66); D Jones, H Bennett (rep: RHibbard, 53), A Jones, I Gough (rep: L Bateman, 77), A-W Jones, F Tiatia (rep: T Smith, 66), MHolah, R Jones (sin-bin, 67-77).

Harlequins: T Williams (rep: S Stegmann, 74); ETaione (sin-bin, 40+2-48), D W Barry, T Masson, CAmesbury; W Luveniyali, A Gomarsall; A Croall, TFuga, M Lambert, J Percival, G Robson, CRobshaw (rep: T Guest, 77), N McMillan (rep: Guest, 26-33), P Davies.

Referee: T Wigglesworth (England). Attendance: 8,057.