Argentine striker Juan Sara scored a wonderful second-half hat-trick as Dundee took the honours in the 107th city derby to inflict more misery on the ten men from Tannadice.

Alex Smith's bottom-of-the-table side came to Dens Park looking for their first league win of the season and it could have been so much different as Mvondo Atangana and Craig Easton both saw fantastic efforts come back off the crossbar.

But after the restart Sara provided a stunning treble to make his tally seven for the season and the visitors' troubles were compounded when they had Jason De Vos dismissed for a challenge on Fabian Caballero.

Not to be outdone Dundee had to have somebody sent off and it was player-manager Ivano Bonetti's brother Dario who was sent from the dug-out for his comments after the dismissal.

The visitors though would have given their manager great heart after making an encouraging start and they could have gone in front as early as the second minute.

Marco Di Marchi brought down Mvondo Atangana on the left of the box and from Jamie Buchan's inswinging cross Steven Thompson got a touch which Robert Douglas had to get down well to save.

Just five minutes later and Douglas again saved his side with a double stop when the lively Atangana got away from the defence.

The striker proceeded to cut into the box before firing on target from close range which Douglas could only parry into the path of David Hannah, but the Dundee goalkeeper did brilliantly well to save the midfielder's follow-up.

Dundee, however, came back and made a chance out of nothing in the 15th minute as McSkimming hit a long hopeful ball down field that Sara took in his strike, but he hesitated and Hasney Aljofree made a blocking tackle and keeper Alan Combe cleared.

Aljofree was stretchered off with what looked a bad leg injury as a result and he was replaced by substitute Craig Easton.

But despite the worrying sight Atangana almost put the visitors ahead in the 21st minute and had it hit the net instead of the woodwork it would have been a strong contender for goal of the season.

The Cameroon international lost his balance as Hugh Davidson's cross came into the box but he somehow stretched and produced a wonderful overhead kick that beat Douglas, but came off the crossbar.

But the home came agonisingly close to breaking the deadlock in the 27th minute when Ivano Bonetti's corner skidded across the face of goal and Di Marchi was just inches away from diverting it into the net.

Some of the challenges had not been for the faint-hearted but it took 28 minutes for referee Stuart Dougal to produce his first yellow card when he booked United's Jean Licini for a late tackle on Fabian Caballero.

Davidson then joined his team-mate in the book in the 33rd minute for a late challenge on Shaun McSkimming and the game was everything a derby could ask for.

But Juan Sara should have sent the home supporters wild with celebration in the 34th minute when Caballero crossed from the right with the visiting defence caught - but the Argentinian marksman headed just inches wide.

But it was United who hit the crossbar again just two minutes later when Joachim Fernandez played the ball to Easton, just outside the box and he hit a tremendous shot which came back off the woodwork.

United's frustration increased in the last minute of the half when Hannah was shown the yellow card for a foul on Bonetti and the Italian returned the favour moments later with a late lunge on the midfielder which earned him the same fate.

Despite United's near-misses it was the home side who drew first blood just two minutes after the restart following a crucial error from Combe.

Caballero ran at the heart of the United defence before unleashing an awkward 25-yard right-foot shot which the United goalkeeper failed to hold on to and Argentinian striker Sara followed up to side-foot into the corner of the net.

But the derby exploded into wild scenes in the 63rd minute when United were reduced to ten men when Jason De Vos and substitute Kevin McDonald both sent Caballero sprawling near the touchline and the Canadian was the one who was sent to the dressing room.

But ugly scenes followed as Caballero limped off to be replaced by Javier Artero and Dundee's assistant manager Dario Bonetti was red carded for something he said - United boss Smith exchanging angry words with him as he departed.

United were committing more men forward in a desperate search for a point, but Sara could have killed the game off in the 70th minute when Georgi Nemsadze played him through, but the Argentine star's shot was well saved by Combe.

But the duo combined again in the 80th minute to put the derby out of their neighbours' grasp when Nemsadze crossed from the right and Sara picked his spot as he emphatically headed home.

And there was still time for Sara to cap a fine second-half display with his third of the night, which was a carbon copy of the second, as he headed home from Nemsadze's centre to give the blue side of the city something to celebrate tonight.