Sean Holley warns Welsh side they will have to find ruthless streak to reach Grand Final

Their recent form in thumping the Dragons and beating Munster in Limerick is impressive, but closer inspection shows that they have struggled often this season, against even the supposed weakest sides, to hit their straps and seal victory until late on.

They are good, and can be brilliant, as you would expect from a squad featuring All Blacks like Jerry Collins, Marty Holah and Filo Tiatia, and more than a team of Wales internationalists, but Holley acknowledged that they have been struggling to find the finish to avoid nervy climaxes to games.

He said: "We need to be more clinical about things; that is obvious to everyone. We're pleased with the way we are playing, our game plan and system is good, and what has been particularly pleasing has been the number of line breaks we are regularly making. But, line breaks aren't enough to win games, as we saw against Biarritz.

"We've been drumming that message home to the boys – it's about attention to detail. That is the difference between winning and losing when you get to this stage of a competition."

There has been much talk among Ospreys this week of how important it is not only to reach the first Grand Final, but also to win it, which suggests the focus of some is already a game ahead to the meeting of Leinster or Munster, who play in tomorrow's semi-final.

How much that merely adds fuel to the fire tonight – the same might be said for the feelings of injustice over the remarkable 100,000 fine – or how much it might allow some complacency to creep into the psyche, is anyone's guess. Holley insists that there is genuine respect for Glasgow and what the Scots have achieved in reaching this stage.

"We've worked really hard this season, to get to this position and to have a home tie," he said, "but we aren't taking anything for granted or being complacent. We know Glasgow are a very dangerous team.

"We've had a lot of away games in the latter part of the season so it's good to be back at the Liberty Stadium for a big one-off semi-final, where home advantage is crucial. We've won eight on the bounce (at home] and beaten good teams; Leicester, Munster and Cardiff during that run, but we realise that will count for nothing now.

"Glasgow have a good squad, there are plenty of internationals in their ranks and they almost edged us out of second place, so while we are glad to be at home, there is still a lot of work to be done. It will be a difficult night and we know that we will have to raise our game another level again from where we were at last weekend against the Dragons."

The Ospreys are without Wales prop Duncan Jones, due to a broken foot, Lyndon Bateman (knee) and Barry Davies (groin), but such is their strength in depth that that has hardly even registered. They possess quality replacements that could play a defining part in this game if, as is expected, the result is still in doubt heading into the final quarter.

All Black Tiatia adds punch to the back row battle and has also stepped in to stiffen the second row on occasions, while Ian Gough is an experienced Wales lock desperately disappointed at being left out and keen, if he gets on, to show he should be part of the make-up were the Ospreys to reach the final.

Jamie Nutbrown, a Kiwi scrum-half, is another talent primed for the second half, while Nikki Walker proved last week that his nose for the try-line is not dented by having to play second fiddle to Tommy Bowe or Shane Williams. That could be crucial because this is destined to be an almighty car-crash of an encounter that leaves bodies battered and lungs empty of oxygen come the hour-mark.

"It's another memorable occasion in our short history," said Holley. "We're there at the business stage of the competition again which is where we aim to be in every tournament we enter.

"We want to make it to the first ever play-off final, but a very good Glasgow team stand in our way, looking to make their own history. It isn't going to be easy, but we know what is required of us and we are all excited about the challenge."