The three times LV= Cup finalists outscored the hosts 3-2 in tries, but a disciplined performance from Matthew Morgan saw the young fly-half kick 18 points, Tom Grabham also touched down, while 19-year old Sam Davies added five points with his boot after coming off the bench for his first Liberty Stadium appearance.

Just two minutes in the Ospreys were handed the chance to take the early initiative, a penalty awarded for taking out the jumper at the lineout, but Morgan pulled his kick across the face of the posts and wide of the left stick.

It was Gloucester who did get the first points of the night after Morgan Allen was penalised at the breakdown, allowing Billy Burns, a late injury replacement at 10, to slot over three points in the ninth minute.

The Ospreys hit back straight away though, Morgan making no mistake after a penalty for tackler not releasing, just 30 seconds after the restart.

The exchange of penalties continued, Joe Rees guilty of both binding on the arm and going straight to ground, allowing Burns to put his team back in front.

The visitors then showed good patience to work their way into a scoring position through a series of picks and go's after Allen had tidied up messy lineout ball. The forwards worked their way infield, and with a penalty advantage in their favour, Morgan was able to slot over a drop goal to level things once again just past the halfway mark of the opening period.

An extremely long advantage in Gloucester's favour for bringing down the maul illegally didn't go down well with the home support as it meant wing Tom Grabham was called back as he looked to pounce on a loose ball to break free. With the penalty awarded, Gloucester went to touch, the catcalls of the crowd making their feelings clear.

From the resulting lineout, their attempt at an attacking maul ended in the same way with the pack going to ground. The verdict was penalty again, and this time James King was sent to the sinbin. Take three, unsurprisingly, saw Gloucester go for the maul again, and this time they were able to find their way over the line, loose head Yann Thomas scoring the try with Burns converting.

The young Ospreys team were showing plenty of spirit though, and within minutes reduced the deficit through a second Morgan drop goal.

Morgan, Rees and Lloyd Peers then combined to give the Ospreys some go forward, a penalty eventually going their way for offside and Morgan duly brought his team back to within just a point.

The penalties were mounting up against Gloucester, and with the last play of the half the visitors were pinged once again as the Ospreys maul inched forward up the left with the familiar outcome of Morgan putting over the three points with the final kick of the opening 40 to put his side ahead for the first time.

HALF-TIME: OSPREYS 15 GLOUCESTER 13

The heavens opened as the teams retook the field, and an early offside penalty gave Morgan another chance to go for goal but this time he was off target.

Although there had been little opportunity for either team's backlines to move the ball, the game was never anything less than compelling, with Ospreys skipper Sam Lewis and prop Rees showing up well around the field as conditions continued to worsen.

Playing to the conditions, the forwards then put together a series of drives that took them to the line, Matthew Dwyer powering forward twice before Allen was held up short. With the supporters turning up the volume George Stowers thought he'd scored, driving over from close range, only for the TMO to rule he's knocked on.

The Ospreys kept up the pressure, a lovely jinking run from Ross Jones seeing him taking the ball straight back upfield from Gloucester's clearance, and when the visitors skipper Peter Buxton was guilty of killing the ball, Morgan was able to put over the first points of the second half, 18 minutes in, after Buxton had been sent to the sidelines for 10 minutes.

Sam Davies, son of visiting Head Coach Nigel, was then introduced on the hour and his first involvement saw him slotting over a penalty to take the team eight points clear.

Buoyed by that, the Ospreys then run in their first try of the night and it was a lovely team effort. Lewis and Stowers carried well, supported by their fellow forwards, and with the overlap created on the left it was spun wide for Tom Grabham who slid in to score. The angle proved too much for Davies, the young fly-half just failing with his conversion attempt, leaving the score at 26-13 to the hosts.

The visitors weren't going to give up the fight though, and they grabbed their second try through Dan Murphy under the posts, the replacement prop barging over from close range, converted by Dan Robson, bringing them back to within a converted try inside the final eight minutes.

They snuck in front with just two minutes on the clock, a penalty at the scrum allowing them to go to the corner and from the lineout the pack rumbled ominously close to the line before going to ground. The referee felt they had been halted illegally and headed under the sticks, Robson's second conversion putting Gloucester in front by a solitary point, by which time there was under 60 seconds remaining.

All credit to the young Ospreys, who by now included four teenage debutants off the bench, as they showed spirit and resolve combined with no little maturity, to steal the game back at the death. A Gloucester lineout on the right hand side was snaffled, swift ball allowing Tom Habberfield to dart through the smallest of defensive gaps before handing on to Allen and the number eight was driven over from eight metres out to score the winning try, young Davies stepping up to round off a great night with the conversion.