Gloucester moved to within 80 minutes of their fifth European Challenge Cup final with an attritional win over Ospreys at Kingsholm.

Ospreys led through Keelan Giles' spectacular try but Seb Blake mauled Gloucester's only try to keep it tight in the first half.

Argentina fly-half Santi Carreras kicked six penalties to secure victory.

Gloucester have been cup specialists this season, winning the Premiership Rugby Cup and advancing to the last four of this competition despite a struggle in the league, where they have lost 10 of their 14 games so far.

They faced an Ospreys side fresh from victory over Sale Sharks last week, and who were expected to pose problems from set-pieces at Kingsholm.

The Welsh side's line-out and scrum malfunctioned, however, but after Carreras had edged the home side ahead, the visitors provided the highlight of the contest just 14 minutes in.

Scotland international Adam Hastings, back for his first action after three months out with injury, attempted a chip kick that dollied into the hands of Australian full-back Jack Walsh.

He caught the Gloucester defence cold with a turn of pace that opened up the right side of their defence, and once he fed Ospreys leading scorer Keelan Giles with open field ahead of him, there was only going to be one outcome.

Carreras and Owen Williams exchanged penalties, but it was to be the last time Ospreys were ahead as the home side turned the screws up front.

They drove over from a five-metre line-out, Blake emerging with the ball, and with Carreras and Owen Williams again nailing penalties, there was just a point between the teams at the break.

Gloucester turned it up a notch in the second half, and Ospreys were repeatedly penalised for forward offences as Zach Mercer and Ruan Ackermann applied the pressure and the scrum got the upper hand.

Carreras has the highest kicking success rate in the Premiership this season, and he simply booted the life out of the Bridgend side with three penalties that went without reply.

Gloucester director of rugby George Skivington:

"After missing so many tackles in our league fixture against Bristol [a 33-24 defeat], we've had a big focus on our defence in the last two weeks so I'm really pleased at how we went in that area.

"We knew Ospreys would go hard at the breakdown and they got into us early on and caught us on the counter with an excellent try.

"Despite it being only 14-13 at the interval, we were happy we were doing the right things but overall we weren't accurate enough.

"We are lucky to have secured a number of knock-out games at home so far this season and the more we bring to Kingsholm the better."

Ospreys defence coach Mark Jones told BBC Radio Wales:

"I'm really proud of the effort, there was no lack of that, and there was some quality there in patches, but giving away 15 or 16 penalties, and the unforced errors around different areas of our game, means it's going to be very difficult to win away from home in a quarter-final.

"You get what you deserve sometimes and we probably deserve to come out on the losing side based on the penalty count and the errors.

"We've played better, and we knew we needed to play well to win away from home."

Gloucester: Santi Carreras; Jonny May, Max Llewellyn, Seb Atkinson, Jake Morris; Adam Hastings, Stephen Varney; Jamal Ford-Robinson, Seb Blake, Kirill Gotovtsev, Freddie Clarke, Freddie Thomas, Ruan Ackermann, Lewis Ludlow (capt), Zach Mercer.

Replacements: Santi Socino, Mayco Vivas, Fraser Balmain, Albert Tuisue, Jack Clement, Caolan Engelfield, Charlie Atkinson, Chris Harris.

Ospreys: Jack Walsh; Luke Morgan, Keiran Williams, Owen Watkin, Keelan Giles; Owen Williams, Reuben Morgan-Williams; Gareth Thomas, Sam Parry, Tom Botha, James Ratti, Adam Beard, Harri Deaves, Justin Tipuric (capt), Morgan Morris.

Replacements: Lewis Lloyd, Nicky Smith, Rhys Henry, Huw Sutton, Morgan Morse, Luke Davies, Dan Edwards, Max Nagy.

Referee: Pierre Brousset (Fra)

Assistant referees: Tual Trainini (Fra) and Jeremy Rozier (Fra)

TMO: Denis Grenouillet (Fra)