Henrik Larsson's lethal hat-trick put Celtic back on course for the double after having their historic back-to-back treble dream snatched from them by arch-rivals Rangers.

Manager Martin O'Neill found a Union Jack in his front garden after watching his side lose to their Glasgow rivals in the semi-final of the CIS Insurance Cup in midweek during extra-time.

His players, however, and Larsson in particular produced the kind of response he was looking for to make Dunfermline pay and move them a step closer unfurling their own championship flag.

John Hartson and Didier Agathe also got in the act as Celtic moved 16 points clear of Alex McLeish's men with just 10 games remaining before Rangers play later tonight.

The night, however, belonged to Larsson who enjoyed himself after coming under fire from the critics for failing to matching his Golden Shoe haul of last season.

The striker never hides however and despite missing an early spot-kick he went on to hit the net three times.

The match did not begin too well for him though as he squandered a great chance to give the defending champions the perfect start from the penalty spot after just three minutes.

Referee John Rowbotham adjudged Youssef Rossi to be holding Hartson and pointed to the spot, but Scott Thomson dived superbly to his right to turn his effort away.

The Dunfermline keeper again did well just a minute later when the ball broke to the Swede in the penalty box, but Thomson dived bravely at the feet of Larsson to deny him.

But Celtic poured on the pressure and Larsson made amends with an opportunistic opener in the 13th minute.

Bobo Balde rose at the far post to divert Alan Thompson's corner back across the face of goal and the Swede dived to head home from close range.

Hartson went agonisingly close to increasing Celtic's lead in the 19th minute when Agathe whipped in a dangerous cross and the Welshman blazed a header just past the post.

The visitors needed to dig deep to stay in the game, but they started to give the ball away on too many occasions while Thomson was doing his best to keep his team-mates in the game.

Marco Ruitenbeek's replacement, however, was beaten a minute later by Paul Lambert's shot from inside the box, but Thomson got back to make a vital clearance.

Under-pressure Thomson again denied Celtic on the half hour as Larsson found Hartson, but the agile keeper got down well to his right to divert the ball wide.

The visitors retaliated moments later with a good move as Mike Panopoulos' cross from the right was caught on the volley by Crawford, but Douglas got down well to save by his post.

Dunfermline, however, were unable to hold out for much longer as Celtic doubled their advantage through Larsson, although Hartson deserved credit for his part in the goal.

Moravcik found the Welshman and his chip to the back post was bundled over the line by the Swede for his 22nd goal of the season.

The heads of the Dunfermline players dropped and Hartson deservedly got his reward with a goal of his own a minute later.

Thompson's free-kick broke off the wall and sat up nicely for him to stroke the ball past Thomson and into the corner.

Rossi lost his composure and was booked soon after before Larsson brilliantly completed his hat-trick.

Hartson again was the provider as he slid the ball to his team-mate, but it still needed an exquisite finish as he drew Thomson before chipping the ball over him and into the empty net.

The game lost its spark after the break although Moravcik tried to conjure up something special for the subdued home crowd with a twist and cross, but nobody could get on the end of it.

Agathe also brought the game to life with a pacy run down the right flank before finding substitute Jamie Smith at the back post, but Thomson got down well to save his header.

Hartson tried an audacious chip from inside the box in the 75th minute which bounced just wide before the home side completed the rout through Agathe three minutes later.

Hartson played the ball through to Thompson and his cut-back was fired emphatically into the roof of the net by the winger.

Larsson could have bagged his fourth of the afternoon late on, but his chip was saved by Thomson.

The Swede, however, had already had his say and looks set to score many more goals between now and the World Cup.

Teams

Celtic: Douglas, Balde, Sutton, Mjallby (Crainey 74), Agathe, Lambert, Lennon (Smith 60), Moravcik (Maloney 74), Thompson, Larsson, Hartson.

Subs Not Used: Gould, Petrov.

Goals: Larsson 13, 32, Hartson 38, Larsson 43, Agathe 73.

Dunfermline: Scott Y Thomson, MacPherson (McGroarty 78), Skerla, Rossi (Bullen 45), Scott Thomson, Nicholson, Mason, Panopoulos, Dair, Crawford, N'Diaye (Nish 60).

Subs Not Used: Harrower, Nicholls.

Booked: Rossi.

Att: 58,590

Ref: J Rowbotham (Scotland).