DAMIEN Duff was today ruled out of Rovers' FA Cup showdown with Arsenal at Highbury.

The Republic of Ireland international damaged his shoulder when he was sent tumbling in the box during the second half of Wednesday night's Cup triumph over Bolton.

And, though X-rays yesterday revealed the injury was not serious, Graeme Souness has had to rule Duff out of Rovers' mammoth Cup quarter final clash with the Gunners.

"Damien fell awkwardly on his shoulder when we thought we should have had a penalty and it's still painful," said the Rovers boss.

"He had an X-ray yesterday which revealed nothing is broken but we have got to have our eye on the big picture with Birmingham on Wednesday as well."

Souness has been boosted, however, by the news that Alan Mahon and David Dunn have both been passed fit for the clash.

Mahon picked up a shin injury on Wednesday night while a toe problem kept Dunn out altogether.

But both are back for the clash and Dunn is relishing the prospect of coming face-to-face with controversial Frenchman Patrick Vieira.

"I want to measure myself against the very best -- and they don't come much better than Vieira," said Dunn.

"I want to know if I am good enough to match myself against such world class players.

"I have always been a confident person and I am sure we can match them in every way.

"Playing in such high profile games gives you the chance to show others what you are made of.

"And perhaps Sven-Goran Eriksson might be watching as well."

Dunn has already turned it on for the England boss on a previous occasion this season when he starred in Rovers' 4-1 demolition of Bolton at the Reebok a fortnight ago.

And, whatever the result tomorrow, the 21-year-old midfielder believes Rovers have already made great strides under Souness's shrewd management.

"We all feel we should be up there with the likes of Arsenal, so we're not afraid of them," said Dunn.

"This game on Saturday will give us a chance to show Arsenal what we can do.

"But whatever happens, hopefully, next season we'll be mixing it with them as well as Manchester United, Liverpool, Chelsea and Leeds."

Souness will recall Henning Berg and John Curtis to his squad after both were rested in midweek against Bolton.

But Craig Short is absent through suspension after picking up his fifth booking of the season in the 4-1 League victory over Wanderers a fortnight ago.

Rovers are likely to choose from: Friedel, Curtis, Bjornebye, Berg, Taylor, Flitcroft, Dunn, Duff, Mahon, Hignett, Jansen, Bent, Hughes, Berkovic, Keller, McAteer, Johnson, Kelly.

Meanwhile, Arsenal are looking to secure an FA Cup semi-final spot at the first time of asking to avoid a fixture pile-up which could harm their season.

The Gunners' vital Champions League clash against Bayern Munich is already looming next week and if they were to draw against Rovers, the replay at Ewood Park would take place on Monday March 19, with their Premiership clash against Aston Villa being moved from the day before to the Saturday morning.

And that would leave three games that could decide their season taking place within the space of just five days.

Beating Rovers at Highbury, however, would resolve that situation, as well as ensuring none of Arsenal's England stars are involved in a game during the week leading up to the World Cup qualifier against Finland.

Boss Arsene Wenger is without striker Kanu, who is away on international duty with Nigeria.

Martin Keown is also still out with a knee injury, while Ray Parlour is close to competing for a first-team place again after a hamstring problem.

Arsenal are likely to choose from: Seaman, Dixon, Adams, Grimandi, Cole, Pires, Lauren, Vieira, Ljungberg, Wiltord, Henry, Bergkamp, Edu, Malz, Parlour, Luzhny, Vivas, Manninger.