CELTIC took a significant step towards making Lionel Messi a very happy man by defeating Kilmarnock 4-1 - with Leigh Griffiths a hat-trick hero from the bench.

The Barcelona icon has added to his bucket list a return visit to Celtic Park on Champions League duty.

Ronny Deila would be delighted to oblige the Argentinian.

But first things first, his Hoops have to grab the only qualifying ticket on offer by making it four titles in a row.

Now eight points clear of Aberdeen with the same number of games played, courtesy of goals from Kris Commons and sub Griffiths, the finishing line can be crossed when they go to Pittodrie on May 10 - or earlier if Celtic keep on winning and the Dons drop any points before then.

With the post-split fixture list finally revealed, the path to glory - or a monumental car crash - is now clear.

For a few days, though, the title can be put to one side while Deila and his players focus on ensuring it can be the major part of historic Treble.

For this, they must defeat Inverness in Sunday's William Hill Scottish Cup semi-final at Hampden and set up a thrilling climax to the campaign at the National Stadium on May 30.

That will be 11 months after their season kicked off, and Deila is wary of fatigue setting in - Stefan Johansen and Emilio Izaguirre have both played over 50 games - at the most crucial point of the campaign.

Despite this scoreline, there are certainly signs the Green Machine is beginning to creak a little.

They struggled to move up the gears as they were held to a 1-1 draw at Inverness.

Hence the reason Deila again rang the changes for the match against bottom-six-doomed Killie.

In came Commons, Adam Matthews and James Forrest.

With the striker rotation system showing no signs of slowing up, birthday Bhoy John Guidetti, was also given the gift of a starting place, even though the future of the now 23-year-old appears less and less likely to be here.

The Swede's tally of 14 early-season goals had kept him as top scorer this season, until Griffiths overtook him last night.

But to put that into context, between them, central defenders Virgil van Dijk and Jason Denayer have found the net as often as Guidetti this season, while other non-strikers, like Johansen and Commons, are just behind.

Indeed, Van Dijk and Denayer both had good opportunities to increase their goal return in the first half against Killie, but both glanced headers wide.

So Guidetti - who did not threaten at all in that stagnant opening 45 minutes, except for a free kick which did not clear the wall, and rarely showed after the break - has work to do if he is to convince Celtic it is worth getting into any kind of wages war with the likes of Feyenoord for his future services.

Put bluntly, Celtic are getting more bang for their buck from several others - especially Griffiths - which has been the case for a number of months now.

Of course, there is still time to be a hero before the prizes - and contracts - are decided.

But it is more important that Celtic come together again as a team and collectively rediscover the form which has put them in this strong position.

This is unknown territory for Deila, but he felt comfortable he knew what his side would be facing against Kilmarnock.

The Norwegian seer predicted Gary Locke's side would try to hit them on the counter-attack and with set- pieces, leaving the Hoops to have the bulk of possession and onus on creativity.

To be honest, in the first half, Killie didn't even do the minimum predicted.

The brightest thing about them was their Barca-esque, day-glow orange strip.

They played like a team whose season was over, which might not be the case if they don't work hard enough to keep out of the battle to avoid the play-off place.

So it was a massive shock to the Celtic system when they found the courage to get forward and open the scoring five minutes after the break.

Darryl Westlake cut in from the left wing and tried a speculative shot from 25 yards.

It deflected off Denayer, wrong-footing Craig Gordon, and found the back of the Celtic net.

It may have been the flick of a switch which the Hoops needed to get going, and within 16 minutes they were ahead.

Commons was the scorer of the first and the creator of the second.

On 59 minutes, he made a loose headed clearance his on the edge of the box and rifled a shot into the postage stamp corner.

Griffiths was already warming up to come on for Forrest as the ball hit the net.

He had only been on for seven minutes when Commons stood up a cross to the back post which the little striker nodded down and in.

Order restored, the relief was palpable as nerves were sewn back together.

Which might have explained why scoring suddenly became so much easier. Well, for Griffiths, if not for Guidetti.

The Hibee fan's alleged choice of songs might not make him too popular in certain areas of the country, or with the Procurator Fiscal.

But his finishing is music to the ears of Hoops fans around the globe.

Griffiths' 22-yard rocket, which flew in off Craig Samson's right-hand post, was one of his better ones for the club he joined 15 months ago.

And he made it a hat-trick five minutes later when he got clear of the tiring Killie defence on the left and shot across Samson and in at the far post.

Between goals, Gordon had to make a terrific save to prevent Nathan Ecclestone reducing the Leigh-way.

But by the end, Killie were happy to hear the final whistle, safe in the knowledge they won't have to face any more top six sides this season.