A VICTORY for Blackburn Rovers at Old Trafford on Sunday could be something of a double-edged sword.

On the one hand, it would provide further tangible evidence that Rovers are capable of mounting a sustained charge for a top-four place.

But on the other, it would also intensify the debate about Mark Hughes being the natural successor to Sir Alex Ferguson.

Like it or not, there's no question Hughes is the red-hot favourite to replace Fergie when he eventually decides to step aside.

Of all the Fergie fledgings who have gone into management, Hughes is unquestionably the most successful, having first proved himself as a boss with Wales, before completely reviving the fortunes of Rovers.

In contrast, Steve Bruce has spent the last few years yo-yoing between the Premier League and the Championship, and once again his Birmingham side are scrapping at the wrong end of the table.

The honeymoon period is also over for Roy Keane, who did a marvellous job of leading Sunderland to promotion last season, but is now finding life a hell of a lot harder in the Premier League.

Keane may well go on to make a great manager in time but right now, he's got a long way to go to emulate what Sparky has achieved during his short time as a top-flight boss.

Then there's Bryan Robson, or Captain Marvel' as the United fans used to call him during his peak as a player.

Having been charged with the task of leading Sheffield United straight back into the Premier League following their relegation last May, Robson's Blades are currently treading water in the bottom half of the Championship, level on points with managerless Burnley.

Bryan was a great player in his day, but he's hardly proving himself to be a great manager.

In the meantime, Hughes and Rovers continue to go from strength to strength.

Having guided the club to two successive top 10 finishes and three cup semi-finals during his three years in charge, Sparky is now talking about the possibility of breaking the top four's dominance, which would be an incredible achievement.

It's hardly surprising then that Hughes' name is starting to be linked with some big jobs: Chelsea, Tottenham and Newcastle, to name just three, over the last few months.

However, the one he really appears to want is currently not available and, thankfully for Blackburn fans, that looks like it will remain the case for a while yet.

Whatever you think of Sir Alex Ferguson, it's impossible not to admire his staying power.

Earlier this week, Fergie celebrated 21 years in charge at United - a remarkable feat in an age when managers get sacked on a whim.

During that time, the 65-year-old Scot has won virtually every major honour the game has to offer, yet his hunger to succeed remains as undiminished as ever.

Now Fergie seems to be relishing building an exciting new team around the likes of Wayne Rooney, Cristiano Ronaldo and Carlos Tevez and, as far as Blackburn fans are concerned, long may that continue.