Not even Sir Alex Ferguson could complain about Nani's dismissal in United's 1-1 draw at Aston Villa.

Overwhelming evidence has not stopped the fiery Scot from voicing his displeasure with referees in the past - but not on this occasion.

"Naive," was how Ferguson described Nani's two-footed challenge on Stiliyan Petrov, which earned him an instant red card - and it is hard to argue with the United manager, who went on to point out the Portuguese winger was not a "malicious" player.

Ferguson's acceptance of referee Peter Walton's decision is less likely a sign of a softening of his own ferocious desire to win, more an indication of the shifting state of the game.

Traditionalists complain the art of tackling has all but gone out of football.

The likes of Paddy Crerand, Nobby Stiles, Bryan Robson and Roy Keane have almost become extinct in an age when the last two winners of the Champions League took the title without a traditional midfield enforcer.

United's failure to follow up their 2008 success against Barcelona last year was largely put down to the absence of Darren Fletcher - but as important as the Scottish international has become to Ferguson's system, he could only be described as a pre-watershed version of a true midfield hard man like Crerand.

Ferguson did not complain about Nani's sending off because he couldn't.

FA rules are perfectly clear about two-footed challenges.

"The ruling for a two-footed challenge is that the moment a player leaves the floor, he is not in control of his own body," explained Referees' Development Officer for Manchester FA, Peter Roberts.

"If he takes the ball cleanly, it is a free-kick and a caution. If he takes the ball and the man, it is a free-kick and a dismissal for serious foul play.

"If he takes nothing of the ball and only the man, it is a dis- missal for serious foul play. The only instance in which he can escape a dismissal is if he takes the ball and not the man."

As Petrov's foot was behind the ball as Nani made contact, the Portuguese winger was guilty of taking the man as well - malicious or not.

Rules

The spirit of the rule is clear and understandable.

At high speed how can any player know without a shadow of a doubt that they will be able to avoid causing a serious injury when hurling themselves through the air at an opponent?

The moment that player takes flight he is endangering the safety of an opponent. And whether or not done with intent, it is a reckless act.

So is it a case of a softening of the game or a necessary measure to ensure the safety of footballers?

Had the tackle from behind been outlawed sooner, Marco van Basten's career may not have been cut so tragically short.

One of the finest strikers in the history of the game was forced to hang up his boots at 29.

The three-time European Footballer of the Year scored 218 goals in 280 appearances for Ajax and AC Milan, winning two European Cups.

Were Petrov's feet as quick as, say, van Basten's, then Nani's tackle may have looked significantly worse.

Still, there is an argument to say the art of the tackle is being taken away from the game.

Players like Crerand, Robson and Keane were so popular because of their full-blooded nature - and each of them were outstanding footballers in their own right.

While the outlawing of the tackle from behind and the two-footed challenge can only be for the better of the game, there is a general feeling that tackling is becoming a dying art.

Pressure

City legend Mike Doyle was famed for his fearsome tackling and believes football will be poorer if it loses its hard men.

"When I was playing, tackling was considered an art form," he said. "Referees are put under so much pressure nowadays to clamp down on anything seen as a hard challenge.

"I didn't think Nani should have been sent off. It wasn't like he went for the man. He went for the ball and got it.

"Football was all the better for its tackling in my day. Fans love those sort of players. I played with the best player in the country at the time in Colin Bell, but my favourite player was Mike Summerbee.

"Full backs used to be terrified of coming up against him. But if he played now, he'd be sent off six times a season."

United European Cup winner David Sadler believes the nature of the modern game no longer lends itself to tackling.

"The art of tackling has gone because the game is so much faster," he said.

"In my day it was much slower and therefore easier to tackle. Nowadays it's so fast that you struggle to make a clean tackle, and the slightest touch means players go flying just because of the momentum.

"There are very few ways in which you can tackle legally these days, but on the whole, I think the game is better for it.

"I played in a great team and at a great time, but I think the game is better now. Now players are given more of an opportunity to show what they can do.

"The likes of football's hard men are becoming a dying breed. There are certainly very few hatchet men nowadays, where as the game was full of them in the 60s and 70s."

Are there any true hard men left in the Premier League, and if so who are they? Have your say.