New Sunderland midfielder Liam Miller has admitted his frustration at his lack of opportunities at Manchester United.

The 25-year-old Republic of Ireland international joined Roy Keane's Wearside revolution last week after managing just 22 senior appearances in his two seasons at Old Trafford.

Miller, who played 33 games on loan at Leeds last season, is now looking to revive his career at the Stadium of Light.

He said: "It was very frustrating. I was part of a massive club at Manchester United and I wasn't playing.

"I need to be playing regularly. Sunderland came in with a chance for me to fight for a place in the team, so I jumped at the chance.

"I am very happy to be here and training and just to fight for my place in the team."

Miller joined United from Celtic on a free transfer during the summer of 2004, but managed just 11 starts, only three of them in the Premiership.

Signed as a potential successor to Keane, he tasted Champions League football at Old Trafford, but could not force his way into Alex Ferguson's plans often enough for his liking.

Miller was away with the Republic of Ireland squad preparing for Saturday's Euro 2008 qualifier against Germany when Keane's call came.

However, he admitted his mind was made up virtually on the spot.

Miller said: "When I got the phone call, my decision was pretty much made there and then, to be totally honest.

"I was training with the international team, and they were very good to let me come over and speak to Sunderland, and it was done and dusted within a couple of hours."

The chance to link up with a man who has achieved legendary status in their native Cork proved simply too attractive for Miller to resist.

He knows what Keane will demand from his players, but is relishing the chance to prove himself.

Miller said: "He was a world-class player, in my opinion. Luckily enough for me, I got to play with him once or twice at Manchester United and it was a pleasure to play alongside him.

"He was a great player and I am sure he is going to take that into management. I was just very happy when the move came about.

"I just have to get my head down in training, work hard and hopefully give the manager here a problem so he cannot leave me out of the side."

Like his fellow newcomers, Miller will hope for a chance to impress when Keane heads for the dug-out for the first time at Derby on Saturday.  PA