THE Ospreys came close to ending their LV= Cup campaign by claiming the scalp of the English champions, but were edged out 16-12 by Harlequins in a gritty encounter at the Brewery Field.
Bath's 32-5 win at Gloucester on Saturday meant the Ospreys had already been eliminated before kick-off, but Harlequins had a 100 per cent record to defend and a place in the Anglo-Welsh competition's semi-finals to secure.
It looked ominous for the hosts when Harlequins sped into a 13-3 lead and, although four penalties from Matthew Morgan brought the Ospreys within a point of their opponents, the visitors made sure of victory with Ben Botica's late penalty.
The visitors came to Bridgend aiming to progress to the last four as the top seeds and, although they were beset by a number of international call-ups like the Ospreys, the Aviva Premiership leaders named a strong side.
The Ospreys, meanwhile, opted for another youthful line-up at a Brewery Field which had been submerged under water only a few days earlier.
The ground staff did a commendable job in preparing a playable surface from what could have passed as the home ground of Atlantis RFC last week, though the Ospreys might have been hoping their illustrious rivals would struggle with the soggy conditions.
For a team who have qualified for the Heineken Cup quarter-finals as the top seeds, the claustrophobic confines of the Brewery Field might have been a culture shock for Harlequins.
But the London outfit adjusted to their new surroundings swiftly, through a combination of a powerful pack which held the upper hand at scrums and a backline which found its groove with some slick early attacks.
Having won 19 of their 22 matches this season, it was no surprise to see Harlequins begin this encounter with confidence, though it was the Ospreys who took an early lead.
Morgan made a brilliant darting break into the visitors' half and, although the jet-heeled fly-half was stopped just short of the Quins' 22, he struck a penalty shortly afterwards to put the Ospreys 3-0 up.
They were soon pegged back as Harlequins controlled possession and flexed their muscles in the scrum to force two penalties, both of which were converted by Ben Botica, son of former Llanelli player Frano.
Holding a 6-3 lead, the visitors began to crank up the pressure and came within inches of scoring the game's first try when wing Sam Smith charged down a Morgan clearance but failed to ground the ball before it trickled beyond the dead-ball line.
Conor O'Shea's side were more clinical when they next attacked the Ospreys' line, with fly-half Rory Clegg passing to centre Matt Hopper, who cut inside on an incisive angle to scythe through from ten yards for the game's first try.
Botica converted to give Harlequins a 13-3 advantage, though Morgan chipped away at the deficit with his second penalty.
The former Wales Under-20s playmaker added another three points to see them trail 13-9 at half-time, and they could have snatched the lead soon after the restart.
With daring ambition and deft handling, the Ospreys moved the ball out wide to wing Dafydd Howells who chipped ahead and appeared to have the beating of his opposite number Seb Stegmann before the ball bounced into touch.
Morgan hit his fourth penalty to reduce the deficit to 13-12 and, with an hour played, Steve Tandy's side looked to take control of the tie by bringing on the experience of Duncan Jones, Ian Gough, George Stowers and Kahn Fotuali'i.
The seasoned quartet helped the hosts dominate possession but, with Harlequins in control of territory in the crucial closing moments, the game appeared to be slipping from the Ospreys' grasp.
With three minutes left, they were handed their final shot at victory as they were awarded a penalty just inside the Harlequins half. Morgan boldly opted to kick for goal but the ball faded short and wide, and Botica then sealed the Harlequins' win as he sent a penalty, the final kick of the game, through the posts.