After an uneven and often miserable season, the one constant for Celtic has been reserving their best form for Aberdeen and today was no different at Parkhead.

Tommy Johnson led the way for the home side with a hat-trick as after a series of shoddy displays in the past month they finally put on an exhibition for their beleaguered support.

Certainly the Aberdeen defence was again to Celtic's liking as, with yet another emphatic win, they extended the aggregate scoreline in this season's five meetings with the Dons to a remarkable 25-1.

Johnson put Celtic in front after 25 minutes and that lead was doubled courtesy of a howler from Jim Leighton in the Aberdeen goal who fumbled a long distance Lubomir Moravcik effort.

Moravcik then produced the goal of the game a minute before the break before Johnson, beset by injuries since joining Celtic, again showed what he can do when fully fit.

In only seven starts this season, Johnson has managed 11 goals, including two strikes in four second-half minutes today to inflict more suffering on Scottish Premier League bottom club Aberdeen.

The Dons had the kind of afternoon which started badly then got worse, but at least they finally managed a goal in response to their maulings through Robbie Winters' 64th-minute consolation.

Johnson was returning for Celtic to replace the injured Mark Viduka, who twisted an ankle in training on Friday, while Stewart Kerr retained his place in goal ahead of Jonathan Gould.

Mark Burchill made a lively start to the game and could have claimed a personal hat-trick within the first 10 minutes with more assured finishing.

Firstly he drilled a low shot into the side-netting after a neat Eyal Berkovic pass then, moments later, blazed over from close range when well-placed.

On 10 minutes, Burchill was perhaps more unfortunate when he saw a flicked header from a Moravcik corner cleared off the line by Aberdeen's Andy Dow.

The Dons were forced into an early switch when Cato Guntveit, only just back from injury, was taken off with a knock to be replaced by Derek Young after 17 minutes.

It was Johnson who put Celtic in front with a goal out of virtually nothing, cutting inside with purpose before netting with a fierce strike from the edge of the area for 1-0.

That lead was almost doubled in an instant when Burchill dashed onto a through ball from Moravcik, but, for once, the Aberdeen backline held firm against the pressure.

Celtic were gifted a second goal after 34 minutes after a dreadful error from veteran keeper Leighton who misjudged a long-range effort from Moravcik and paid the price.

The Slovakian's 20-yard shot hit Leighton on the chest and then looped over the keeper and in the net in freakish fashion - and that was the cue for Celtic to turn on the style.

At once their football was more flowing, first Leighton denying an onrushing Burchill, then, from the resulting Moravcik corner, Stubbs seeing a header drift just over the bar.

Johnson fired over a shot on 39 minutes, before a weaving Healy run almost saw the youngster claim a Celtic third only to be denied by Leighton.

Celtic did make it 3-0 before half-time, however, when Moravcik teased his way past Thomas Solberg before crashing the ball into the roof of the net with Leighton powerless.

Aberdeen pulled off Arild Stavrum at the break, the Norwegian forward barely getting a kick in the first 45 minutes, and brought on Hicham Zerouali in his place.

The Dons spurned a clear opening within two minutes of the restart when Paul Bernard's pass released David Rowson, but the midfielder's finish was too casual, Kerr saving a weak chip.

That was to be punished after 51 minutes when Celtic extended the scoreline to 4-0, Johnson this time surging in from the right before rifling a low shot into the bottom corner.

Another sharp finish saw Johnson claim his second hat-trick of the season, after an earlier trio against Dundee, when he seized on a Whyte error to score with a low volley after a Burchill cross.

Celtic gave a debut to #100,000 recruit from Raith, Paul Shields, as a 61st minute substitute for Burchill and he could hardly have picked a more relaxing moment for a debut.

After 63 minutes, Moravcik could and should have claimed his hat-trick but when played in by Berkovic sidefooted badly wide when 6-0 looked a virtual certainty.

Instead the scoreline was to become 5-1 as Aberdeen finally broke their duck against Celtic this term when Winters beat the offside trap, rounded Kerr and slid the ball into an empty net.

Moments later, Winters fired an angled drive inches wide of the mark to prompt the visiting support to issue a chorus of `easy, easy' followed by `we're going to win 6-5'.

Kerr ensured there would be no further consolation for the visitors when he produced a fine one-handed stop to deny substitute Young pulling another goal back.

After 73 minutes, Leighton in part redeemed his earlier mistake by saving magnificently from a swerving Moravcik effort which looked goalward bound from the moment it was struck.

Zerouali then conspired to send the ball over from close range, but Celtic, though a distant second to Rangers for the title, had done enough to again leave Aberdeen outclassed.

Teams:

Celtic: Kerr, Riseth, Crainey (Kennedy 53), Stubbs, Lambert, Mahe (Petta 77), Healy, Moravcik, Berkovic,Burchill (Shields 60), Johnson.

Subs Not Used: Gould, Smith.

Booked: Riseth.

Goals: Johnson 25, Moravcik 34, 43, Johnson 50, 53.

Aberdeen: Leighton, Whyte, McAllister, Solberg, Dow, Bernard, Guntveit (D. Young 16), Stavrum (Zerouali 46), Perry, Winters, Rowson (Belabed 77).

Subs Not Used: Preece, Lilley.

Booked: Whyte.

Goals: Winters 64.

Att: 41,786

Referee: Kenny Clark.