Gloucester 17 Ospreys 0: The "chokers" tag will probably stick to Gloucester until they win either the Guinness Premiership or Heineken Cup – but a battling display at the Ricoh Arena certainly suggested Dean Ryan's men are growing up.

Pitched against opposition of genuine class and reputation, Gloucester dug deep to deny their EDF Energy Cup semi-final opponents with an outstanding defensive effort.

With the dynamic Shane Williams, in particular, threatening to rip Gloucester apart at regular intervals, the cherry and white wall held firm for long enough for Ryan Lamb's right boot to make the difference.

Lamb grabbed the headlines for his 12 points – and there is no doubt the dropped goal which made it 9-0 on 70 minutes ultimately broke Welsh resolve.

But there were heroes all over the field for Gloucester, from the assured Olly Morgan at full-back, right through to the solid Greg Somerville at tighthead prop and the energetic back row of Alasdair Strokosch, Andy Hazell and Gareth Delve.

Fly-half Lamb, who has fallen out of favour at Kingsholm in recent weeks and was only in the team because Carlos Spencer is cup-tied, hopes Gloucester can now go on to banish their reputation as big-match bottlers.

"Everyone has been tagging us as chokers, but we played against what is pretty much the Welsh international team and we put them away," he said. "So I think the confidence in the side is massive at the moment.

"When we got success really quickly, I think everyone expected the trophies to come rolling in. We had that one year where we finished top of the league and played some fantastic rugby but then lost in the final.

"Then, in the second year, we fell at the semis, but I think this year you can see the maturity of the side. Ospreys put us under a lot of pressure but we didn't panic.

"We stuck to our guns, kept to our defensive pattern and we kept them to nil – and not many sides can say they have done that to the Ospreys."

Lamb's third-minute penalty – awarded when man-of-the-match Morgan was obstructed by Gavin Henson and Adam Jones as he kicked ahead – clearly settled Gloucester nerves.

But they spent much of the opening period defending, as Ospreys tested and teased their defence. James Hook missed two penalties, but with him, Williams and Sonny Parker on the field, the Welsh side rarely went more than a few minutes without looking menacing.

When Hook, low on confidence after his earlier misses, sent a penalty to touch, Ospreys should have profited in the form of a try off the line-out – but again Gloucester's defensive intensity proved too much.

Other than Gloucester's tireless defensive work, the opening period was memorable for little else but the match-ending injuries suffered by three of the more celebrated backs on the field – Henson, James Simpson-Daniel and Mike Tindall.

But Williams was at it again shortly after the restart, piercing the Gloucester defence with another mesmeric break – only to be tackled, lose possession and allow Gloucester to counter.

From the same attack, they won a penalty when an Osprey failed to roll away from the tackle, and Lamb made it 6-0.

That was how it remained for more than 20 minutes – thanks largely to Olly Barkley's brave tackle on Marty Holah after the flanker broke through in front of the Gloucester posts.

And when Lamb sensed the opportunity to add three points by dropping a goal after Morgan had brilliantly gathered Lamb's kick ahead, his execution was spot on to take Gloucester into a 9-0 lead.

Welsh frustrations grew, and when Ospreys lost their bind at a scrum, Lamb made them pay by kicking his side into a 12-0 lead.

Again Williams came back at them, but when his break was halted just inside the Gloucester 22, Mike Phillips took over and his wild pass landed in the arms of Iain Balshaw, who tore up-field to seal his side's victory.

And having kicked his side back to Twickenham, Lamb is now eager to erase the memories of their previous trip there – the 44-16 Premiership final drubbing at the hands of Leicester in May 2007.

"It will be massive for the club to play at Twickenham again," he said. "The last time I was there wasn't my best day, but a few years down the line I think I have developed as a player and a person. I think the way I see the game is a lot more mature. Hopefully it will be a different situation the next time I'm there."

Gloucester: O Morgan; I Balshaw (G Cooper 80), M Tindall (capt; M Watkins 33), A Allen, J Simpson-Daniel (O Barkley 41); R Lamb, R Lawson; A Dickinson (C Nieto 37), O Azam (S Lawson 62), G Somerville, W James (M Bortolami 71), A Brown (M Bortolami 5-15), A Strokosch, A Hazell (A Qera 52), G Delve. Scorers: Try – Balshaw. Pens – Lamb (3). Drop goal – Lamb.

Ospreys: G Henson (J Spratt 40); T Bowe, S Parker, A Bishop (D Biggar 72), S Williams; J Hook, J Nutbrown (M Phillips 54); P James (C Griffiths 80), R Hibbard (H Bennett 61), A Jones, I Gough (A-W Jones 29), A Lloyd (F Tiatia 65), T Smith, M Holah, R Jones (capt).

Ref: N Owens (Wales).