Henrik Larsson helped the champions move a step closer to retaining the title with a comfortable victory at Dens Park - before giving them a massive Scottish Cup injury scare.

He hit his 24th Premier League goal in 28 games before hobbling off with what appeared to be a serious hamstring strain.

His Sweden international team-mate Johan Mjallby and strike partner John Hartson eased the pain by securing the points which sees them now needing just five more victories to keep the championship trophy at Parkhead with nine games remaining.

But their hopes of retaining the Scottish Cup look to have been hit by Larsson's injury on the eve of next week's tough trip to Aberdeen - still the only team to beat them in the SPL.

Paul Lambert, who signed a two-year contract extension on Friday, also gave Celtic some concern ahead of their trip north by limping off in the second-half.

The day started out so well for Martin O'Neill's men as they restricted the home side to long-range efforts early on.

The Celtic defence stood off him in the second minute to give the Temuri Ketsbaia the chance to pull off an awkward right-foot shot, but former Dundee goalkeeper Robert Douglas comfortably saved.

Ketsbaia teed up Gavin Rae just three minutes later on the edge of the area, but he was unable to get the power and direction required to trouble Douglas.

But the tide slowly turned with nervous Dundee goalkeeper Julian Speroni giving the visitors hope.

He almost paid for an embarrassing fumble in the 11th minute when he failed to gather Alan Thompson's hopeful punt, but fortunately Barry Smith was behind him to clear the danger.

Referee Mike McCurry began to upset the home fans with some questionable decisions and he stirred them up further in the 15th minute by booking Massimo Beghetto for fouling Bobo Balde.

Their misery was compounded in the 20th minute when Celtic took the lead through Larsson.

Lambert charged into the box and Smith's challenge knocked the ball into the path of the Swede who side-footed home into an empty net for his 29th domestic goal this season.

Speroni looked nervous and again made a hash of Thompson's cross and Fan Zhiyi had to react quickly to put the ball behind.

Chris Sutton, who was again in defence, should have doubled the lead in the 25th minute when Balde directed Thompson's cross into his path, but he shot straight at the Argentinian keeper.

After a bright start, Ketsbaia began to let his frustration get the better of him and he was booked for a foul on Petrov.

John Hartson almost punished the home side in the 33rd minute after Fabian Caballero had given the ball away just outside the box, but his chip just sailed over the crossbar.

Celtic, however, suffered a massive blow in the 39th minute when Larsson hobbled off with what appeared to be a hamstring injury and he was replaced by Lubo Moravcik, who would have his own say in the game.

Thompson became the first visiting player booked in the 40th minute for a foul on Caballero a decision greeted by ironic cheers from the home supporters.

Larsson's departure lifted the home side, but that was short lived as Celtic doubled their lead three minutes before the break.

Mjallby headed Moravcik's cross home from close range after referee McCurry waved play on when it appeared Balde had fouled Speroni.

But with barely a minute on the clock in the second half they should have fallen further behind.

Balde pulled away at the far post to get on the end of Thompson's free-kick, but he headed just past the post.

Bonetti made another change in the 56th minute by bringing Khaled Kemas on for Caballero.

The home side, however, came back into the game and should have reduced the deficit with two chances in the space of a minute.

First Milne squandered a glorious chance as he got on the end of Beghetto's cross, but he headed just wide with the Celtic defence and Douglas struggling to make up the ground.

Douglas then denied Dundee with a brave save from Kemas in the 71st minute and Lambert tackled Ketsbaia as the Georgian sized up to shoot into the empty net.

But Celtic suffered another injury concern as the former Scotland midfielder was hurt in the challenge and hobbled off to be replaced by Steve Guppy.

The champions, however, refused to let that get to them and they killed off the home side in the 75th minute in great style.

Moravcik found Hartson with a wonderful ball and the Welshman controlled it, took his time and then chipped Speroni.

Ketsbaia hit the post with a minute remaining with a dipping right-foot shot, but the damage was already done.

Manager Ivano Bonetti, who is still away in Italy after getting married, would not have heard the jeers at the final whistle as the home support vented their anger at his side and the referee.

Teams:

Dundee: Speroni, Smith, Zhiyi, Del Rio, Beghetto, Romano, Rae, Ketsbaia, MacKay (Artero 45), Milne (Sara 73), Caballero (Kemes 57).

Subs Not Used: Langfield, Robertson.

Booked: Beghetto, Ketsbaia, Romano.

Celtic: Douglas, Mjallby, Sutton, Balde, Agathe (Smith 78), Lambert (Guppy 73), Lennon, Petrov, Thompson, Hartson, Larsson (Moravcik 38).

Subs Not Used: Gould, Crainey.

Booked: Thompson.

Goals: Larsson 20, Mjallby 43, Hartson 77.

Att: 10,642

Ref: M McCurry (Scotland).