Alan Hansen on Sir Alex Ferguson

Ferguson's desire for excellence is as strong as ever

Alan Hansen BBC Sport football expert

Sir Alex Ferguson reaches his latest landmark when Manchester United visit Chelsea on Sunday and he becomes the Red Devils' longest-serving manager.

And a positive result of any sort at Stamford Bridge will leave the 68-year-old Scot eyeing up another in the shape of his latest Premier League title.

It is a tribute to this enduring and uniquely driven great of the game that he is overtaking Sir Matt Busby's tenure of 24 years, one month and 14 days - served over two spells in charge at Old Trafford between 1945 and 1969 and from 1970 to 1971.

From his arrival on 6 November 1986, Ferguson has rebuilt United and secured silverware on a scale that could barely have been imagined in Old Trafford's wildest dreams when he travelled down from Aberdeen to be appointed as Ron Atkinson's successor.

At the start of every season, the most important aspect of any club is the hunger and desire of the players and the manager that leads them. It delivers a telling insight into Ferguson's character that those qualities are burning inside him just as fiercely today as they ever were.

And, with victory over Arsenal on Monday and a trip to Chelsea coming up, Ferguson is involved in the sort of games he relishes. I also happen to believe that if United avoid defeat at Chelsea, he will be well on the way to hitting another target, overtaking the record of 18 titles United currently share with Liverpool.

When you scrutinise the levels of hunger and desire required to maintain success, unless you are an equally special case such as Ryan Giggs or Paul Scholes most players can only maintain this for 10 to 12 years.

Ferguson has done it for 24 years under the most intense scrutiny at Old Trafford and, of course, before that at Aberdeen, where he presided over the greatest era in the Pittodrie club's history.

I can only express my admiration for how Ferguson has handled the pressures of life at the top even more when I place it in the context of my own playing career at Liverpool. Everyone thinks chasing trophies is a wonderful life, and in large part it is, but let me assure you it is not easy on the nerves either.

Ferguson has shouldered that responsibility at a giant of a club for 24 years with huge success, thriving on it and constantly seeking out new goals

You finish one season with success and then you have to go again. The cycle repeats itself if you enjoy continued success and you know if you are the team at the top, as Ferguson's United have been for so long, that every game you play is at maximum intensity because every opponent is just desperate to beat you.

I had it for 14 years at Liverpool and I really felt that pressure in my final season in 1990-91. It came to March of that season and I wasn't sleeping at night. I was lying awake wondering how results would pan out. What if they got three points there? What if we didn't win that game? I knew that my time had come to retire from playing.

Ferguson has shouldered that responsibility at a giant of a club for 24 years with huge success, thriving on it and constantly seeking out new goals. He almost retired in 2002 but obviously wondered what he would do without football.

Manchester United have enjoyed much success under Ferguson

You watch him now and see he was right to shelve that decision. He looks good, wants success for United as much as ever and looks as ready to take on all-comers as he ever has.

And, while he is celebrating a Manchester United landmark, we must not forget the other strands in his incredible career. There are plenty out there who regard his successes at Aberdeen as something that can sit comfortably alongside those he has achieved at Old Trafford.

To break the stranglehold of Celtic and Rangers with the Dons in Scotland was remarkable enough, but he did it over a period of years, as well as beating Real Madrid to win the European Cup Winners' Cup in 1983.

The greats in football are recognised and measured by what they have achieved - and one glance at Ferguson's record confirms he deserves his place in that pantheon.

He came to England to revive United and, as he famously said, to "knock Liverpool off their perch." Well, he succeeded and when he does leave Old Trafford he will leave the most incredible legacy.

Ferguson has produced teams and players to grace the game, sending them out to play in an attacking style to score goals and win matches.

I recall working with Sir Alex with Scotland and he was incredibly motivated and passionate back then. The fact that he remains so today only confirms his status as one of the game's greatest figures.

On a personal level, I have always found him good fun and very affable. I take people as I find them and always enjoy his company. As for his footballing ability, it demands total and utter respect.

While he can be justifiably proud of becoming United's most enduring manager, of even greater interest to him this weekend will be celebrating it with the right result at Chelsea.

You don't need to be a genius to predict it will be close. United took three points off Arsenal on Monday while Chelsea's performance in the second half at Tottenham after Didier Drogba came on was like the difference between night and day.

This is a massive game for Chelsea. If they don't win, it extends their recent indifferent run. But, if they do get three points, the Blues will feel they can revive their season and be hoping midfielder Frank Lampard will be fit to help them achieve it.

I think Chelsea and United are the only serious title contenders, although others will try to run them close. If Ferguson's men avoid defeat and make it at least four points from back-to-back games against Arsenal and Chelsea, they will feel they are cruising.

It would leave United going into Christmas on top of the table, undefeated and entering their traditionally strong second half of the season.

I still harbour doubts about Chelsea's squad, which I feel has a threadbare look about it while United can mix and match theirs against so-called lesser sides and still expect to get results.

It is ironic that after their start to the season, there were some who suggested Chelsea could have the Premier League wrapped up by Christmas. If United draw or win at Stamford Bridge, then I can see them pulling away from the chasing pack.

Ferguson's side have the experience. They have been over the course and lasted the distance plenty of times before. No-one knows the terrain better, or has negotiated it more successfully, than their manager.