CELTIC can tonight take another small step towards securing a domestic Treble by extending their lead at the top of the SPFL Premiership.

Ronny Deila has repeatedly confirmed a clean sweep of trophies in his first term in charge is his target.

The Hoops boss has been joined by John Guidetti and the experienced Craig Gordon, among others, in claiming it is a realistic aim this season.

Celtic are making good progress in that direction, booking a place in the League Cup semi final, the sixth round of the Scottish Cup and leading the race for the title they have won for the past three years.

However, one look at the record books confirms just how tough an ask it is to take a Treble.

In the 67 years that all three prizes have been up for grabs, only Jock Stein (twice) and Martin O'Neill have brought this honour to Parkhead.

The last time was in 2000-01, O'Neill's first season in charge.

Since then, Gordon Strachan and Neil Lennon have come close, but had to settle for doubles.

If Deila can better this at the first time of asking, it would automatically elevate him to the rank of one of the club's most successful managers.

But, as many who have tried and failed will testify, it takes a special manager and group of players to create the Treble yell.

Rab Douglas was a key member of the side which last achieved this feat.

And the man who, at 42, is still playing in goal for Forfar every week, firmly believes the time to start talking about possible Trebles is when you are on your way to Hampden to play the Scottish Cup Final with the first two trophies already in the bag.

Douglas said: "I don't remember us going around talking about Trebles when we were not even half way through the season. I think that's a wee bit premature.

"Certainly, you want to win every game and beat every record. The side I joined was more than capable. That year, they set a record for consecutive clean sheets in the league which stood until Fraser Forster bettered it last year.

"We smashed so many records that year, including consecutive wins. Even when we were three or four up in a game, we kept going for more.

"The winning mentality in that team meant you never took your foot off the gas. As much as the boys up front wanted more and more goals, those of us at the back wanted another clean sheet."

O'Neill's side put the first part of their Treble in place with a 3-0 League Cup final win over Kilmarnock on March 18.

Douglas - who arrived from Dundee in September - was cup tied, but was No.1 in the run to the title they secured with a home win against St Mirren on April 7.

He was also the last line in their challenge for the Scottish Cup, which they lifted with a 3-0 win over Hibs on May 26.

With two legs of the Treble already ticked, the pressure going into the final increased.

But Douglas believes that group of Bhoys had already proved they had an inner strength to match their ability.

"Over the piece, we were so consistent. By the time we won the title, we had lost only one game," he recalled, with no little pride. "So you have got to maintain that consistency of results.

"Good luck to them, but it is a lot harder than you think. I'm quite sure Mr Deila now knows it's every team's cup final when they play against Celtic."

The deeper you go into a successful season, the more prized your scalp becomes. That was a harsh lesson learned by Strachan and Lennon, who freely admit coming up short in their quest to join the Treble Club as managers still hurts.

Cup exits to, among others, Clyde, Falkirk, St Mirren and Morton were among the disappointments, underlining how one bad day at the office can shatter a dream for a season.

Douglas said: "You can maybe rest some players and bring others in because you might still be in Europe and have one eye on those ties.

"But in that game the team might not perform and you can find yourself out of a cup."

If the strikers are mis-firing on any given night, having a solid keeper and defence can at least give you a second chance.

But Douglas freely admits, the Class of 2001 was better known for what they had at the other end of the pitch.

"To be fair, having Henrik Larsson and Chris Sutton up there, our team probably led from the front, with no disrespect to our defenders.

"But Craig Gordon has been immense for Celtic this season, and it's absolutely brilliant to see him back playing. I watched him against Dundee a few weeks ago and he was superb."

What a fairytale return it would be for the 31-year-old if he could be part of a side which enjoyed a clean sweep.

But, although the game in Scotland has changed dramatically in recent years, Douglas does not believe it is any easier to grab a hat-trick of prizes.

"It's 13 years since we won the Treble," he said. "The fact no side has managed it since then tells you how hard it is to achieve. It's certainly not a cakewalk. And, back then, you have to consider the standard of players we were playing against.

"Motherwell were paying £200,000 for decent players. Dundee United were doing the same, so were Aberdeen. Now it's almost all Bosmans in Scotland."

More significant, in the eyes of many, is the fact there is no Rangers presence in the title race. However, Douglas does not subscribe to the theory a treble would be devalued as a result.

"The biggest thing is you are down in the history books for winning a Treble," he insisted. "It doesn't interest me if Rangers are in the league that year or not.

"No matter what, it is there in black and white that you won all the trophies. It's still going to be the pinnacle of any player's career.

"You know you are in the history books and, no matter what, no one can take that away from you. But to do it, you have got to be so consistent in the league and in the cups."