Martin O'Neill will know all about the menace Henrik Larsson represents to his side today.

That was his description of the Swede when Sir Alex Ferguson enticed the striker on a three-month loan to Old Trafford in November.

Indeed, had there been the opportunity to lure Larsson to Villa Park, the Ulsterman would have moved swiftly to make him the fifth member of Villa's branch of Bhoys Reunited, following the acquisition of Stilian Petrov, Chris Sutton, and Didier Agathe (that's not forgetting the manager himself, of course) from Gordon Strachan's side.

But Larsson, the former Feyenoord, Celtic and Barcelona player, who joins from Swedish side Helsingborgs during their close season, understandably decided to answer Ferguson's overtures when the Manchester United manager sought forward cover.

Today on his United debut, in the BBC-televised third round FA Cup-tie at home to Aston Villa, he could be asked to forge a partnership with Ole Gunnar Solskjaer. There will be scepticism in some quarters whether, at 35, Larsson can handle the rigours of the English game which he has never experienced before.

But Villa midfielder Petrov, a Celtic team-mate for five years, insists Larsson has demonstrated that he can perform anywhere, and at any level.

"Of course the Premiership is different, different to any league in Europe, " says the former captain of Bulgaria.

"The pace is so much faster; you don't stand still for a minute, and if you make even a small mistake you are punished for it.

"In every other league you can get away with a few games when you don't have to be at full performance, but in England every team has three or four special players.

That's why the Premiership is the best league in the world."

He adds: "I don't think Henrik will need time to adjust to the pace. He's played at the highest level in the Champions League and in international football. It won't be a problem to him.

"In England you maybe don't know how good he is yet. A lot of people then questioned if he could do it somewhere else, but he went to Barcelona and proved anybody who questioned him wrong.

"He didn't just do well there, he did very well - he won them a European Cup.

People always question top players, but Henrik is a true great. He will always be asked questions but always come back with the answers."

"The manager knows all about Larsson's game, of course, because he was his player for five years, " Petrov said. "He knows what to expect but I don't think he knows how to deal with him."

Asked if there was a way to limit Larsson's potential to score should he make his debut, he added: "Yes - keep him away from the goal.

That's the best you can do."

He suggested it was 'great to see him in a Man United shirt' and had no doubt that he could prosper in the Premiership.

"Of course he can, " said Petrov. "You can see how many players do well at 30, 32, 33 and if you look after yourself it shouldn't be a problem.

"He definitely does that - you'll see how well he looks and how fit he keeps himself."

Villa's £7m recruit revealed that he and Larsson had spoken during the summer of the possibility of re-uniting under O'Neill in Birmingham.

"We joked when Martin got the job that maybe Henrik could come over (Larsson had returned to Sweden to play for his first senior club).

But we thought the manager might be angry with us for picking his team!"

Petrov himself was originally brought to Celtic Park by John Barnes, but his relationship with O'Neill flourished once the Irishman arrived.

There was no surprise when the play-maker with an eye for goal - he scored 63 goals for Celtic over seven seasons - became O'Neill's first signing, a £6.5m purchase, when the new manager succeeded David O'Leary in August.

The 27-year-old Bulgarian has made a fitful start to his Premiership career, as he concedes.

"I think I have been OK;

you can always ask for more, " he says. "I'm very critical of myself. I know I can do better and I will do. I seem to have had so many times that I have nearly scored when the ball has hit the woodwork or been cleared just off the line.

"You go through spells like that sometimes and you know if you keep getting into the good positions then it will happen for you."

He believes that Ferguson has provided an excellent model for what can be achieved if a manager is given time and resources.

"If Martin O'Neill stays at this club a long time then he will build it bigger and bigger and better and better, " Petrov says.

"You can see Sir Alex Ferguson has had many years at Manchester United and built the club and built it more, and Martin can build Aston Villa in the same way, a bit better each year with players who will compete in every game and who will want to win."

Winning is not a word associated with Villa recently. But today could be their opportunity.

All is relative where United's strength is concerned.

But with Louis Saha injured and Wayne Rooney possibly not quite performing at the summit of his powers, this could be the moment for Villa to secure at least a replay in a year when their hosts' priorities are the Premiership and the Champions League.

But then again, with Larsson lurking, who knows? It could all end with Villa blood in the water.