The Ospreys looked down and out at 19-6 adrift after 60 minutes, but wing Nikki Walker’s try and Hook’s nerveless goalkicking – he finished with 17 points from five penalties and a conversion – put them ahead before Stade salvaged a dramatic draw.

Stade replacement Lionel Beauxis landed a 50-metre penalty in the fifth minute of injury-time to level the Pool Three clash after Ospreys flanker Steve Tandy roamed offside.

But Gavin Henson then almost snatched it for the Ospreys with an ambitious drop-goal attempt which drifted narrowly wide.

Stade will win the group and secure a quarter-final place if they beat Italian minnows Calvisano in Paris with a bonus point next Saturday, but the Ospreys could also still progress as a best runner-up by toppling English champions Sale Sharks at Edgeley Park.

Hook’s last-gasp conversion gave the Ospreys a dramatic success against Sale in October, and they could now require further heroics next weekend.

The French club established a sizeable lead through full-back Juan Martin Hernandez’s first-half try, while David Skrela slotted two penalties, a drop-goal and conversion before Beauxis took over kicking duties and rescued the game.

Ospreys wings Walker and Shane Williams both passed late fitness tests, but the home wide went into their biggest game of the season without injured Wales internationals Sonny Parker and Jonathan Thomas.

Stade, beaten 13-8 by the Ospreys in Swansea last season, were boosted by centre Brian Liebenberg and prop Sylvain Marconnet shaking off injury and illness respectively, as they targeted taking a giant stride towards quarter-final status.

The Ospreys suffered an injury blow inside three minutes when flanker Filo Tiatia limped off to be replaced by Andy Lloyd, and Stade’s threat was immediate through a slashing Agustin Pichot which almost sent wing Christophe Dominici sprinting over wide out.

Walker’s tackle prevented a certain try, but Stade soon opened their account through Skrela’s penalty after he scuffed his opening attempt, leaving the home side searching for continuity.

Hook landed an equalising penalty eight minutes later, yet even though the Ospreys attacked aggressively through scrum-half Justin Marshall’s constant sniping, Stade stung them with a try early in the second quarter.

Lock Boela du Plooy had the presence of mind 30 metres out to place a kick behind Ospreys’ defence and Hernandez reacted quickest, outstripping chasing defenders for a score which required confirmation from video official Geoff Warren.

Skrela slotted the conversion, and despite Hook then landing a second penalty, Stade remained far more dangerous with ball in hand as they looked to free the dangerous Dominici at every opportunity.

A Skrela drop-goal and penalty took Stade 10 points clear, and there was little the Ospreys could offer in terms of a positive response as another injury blow on the stroke of half time saw them lose full-back Lee Byrne.

The crowd grew increasingly restless at Ospreys’ failure to make an impression - a consistent stream of penalties awarded against their team by top English referee Chris White merely deepened the sense of frustration – and Stade predictably extended their lead.

Skrela and Henson were both off the field receiving treatment following a clash of heads, but Stade replacement Beauxis proved a capable deputy, making it 19-6 with an angled penalty before a patched up Henson rejoined the action.

Ospreys finally stirred as the closing quarter beckoned. Stade had du Plooy sin-binned, and two Hook penalties in quick succession narrowed the gap to seven points, launching an overdue fightback.

And with 14 minutes remaining, superbly composed phase-play stunned Stade, with Walker rounding off concerted Ospreys pressure by touching down between the posts.

Hook converted, before the Ospreys almost conjured a second try, but the final pass agonisingly eluded a hungry Walker.

It was stirring rugby from the home side, leaving Stade hanging on for even a share of the spoils, yet even that looked beyond them when Hook landed a 40-metre penalty that put Ospreys in front for the first time.

Stade went for broke during the closing seconds, going agonisingly close from a relentless forward drive before Hernandez’s ambitious long-range drop-goal attempt sailed short and Beauxis delivered the equalising blow.