Karna tried to pacify duryodhana and avoid the duel challenge between them. He asked him to surrender in front of pandavas and suggested him to return their kingdom and wealth.
Duryodhana freaked out at karna, he said in a stern voice that karna betrayed him in the moment they needed him most. He reminded karna that it was him, who gave him kingdom, wealth and respect which he never actually deserved as he belongs to a low caste and when he was expelled from taking participation in the competition which held in arena of hastinapur, it's him who stood by him and gave him the right as a 'king' which later helped him to take part in that competition.
Duryodhana further falsely declares that Krishna is manipulating him to attain victory in the war and he will treat karna poor once again after the war ends. Duryodhana assures karna that he still believes him as his best-friend, he will forgive his betrayal and give him an another opportunity to join kauravas.
Karna was stunned knowing how genuine duryodhana is to him as a friend. He felt that he is been lucky to have a friend like him, when he clearly knows, duryodhana is doing all this stuff to get him back to their side. Karna said confidently that he realized his mistakes and now he want to purify them by choosing what he must choose. Karna once again pleaded duryodhana to leave the enimity with pandavas and solve the matter by negotiations.
Dushasana says to duryodhana that karna seems not going to leave pandavas side and asked his permission to order their army to attack on him. Then, duryodhana closed his eyes for a minute remembering the beautiful moments he had with his dear friend. When he opened his eyes, they were turned into red which were mixed up with anger and insult. He hold the grip of his mace and asked karna to pick the weapon.
Karna was confused what he needs to do. He looked at pandavas who were also not happy karna being here except Yudhistira, karna looked at Krishna and Krishna signalled him to accept the challenge.
Duryodhana reminded the condition that he will leave him on karna on his freedom if he able to defeat him, but if he won karna have to behave like a slave for rest of his life and he has to fight from their side in the war. Karna agreed with the terms of the challenge and told him that he will fight with the mace as karna know duryodhana is not a better opponent when it comes to an archery fight.
Karna and duryodhana both entered into a ring and a small but fierce duel took between them. Duryodhana able to give karna a tough match, but karna was also brave in warfares. He used his intellect and knock him severely, karna knew duryodhana's fighting style very well as he was with him for over years.
Duryodhana managed to endure the pain of his injuries and attempted to strike over karna which proved useless due to his divine armour.
Duryodhana was surprised seeing how karna is mastered even in mace fight when he is an archer. Pandavas are too impressed by karna's fighting style and bravery; arjuna and bhima were totally perplexed and looking each other in surprise.
Karna gave a final blow to duryodhana which makes him to fall on the ground, he nearly become unconscious. But managed to re-call his senses and stood before karna, krishna declared karna as winner of the duel and as per the condition, duryodhana has to fulfill his words of respecting karna's decision of surrendering himself and leave him without trying any new moves.
Duryodhana stood and said karn that it's not the end. He leaving him today unharmed, but one day he will have to pay the price for his disloyalty.
When duryodhana leaves, Krishna put his hand on karna's shoulders and expressed how happy he is with him and asked him for a boon. Karna replies that he wants duryodhana to realize his mistakes and end the subject of war. Krishna smiled and said it's not possible as duryodhana already rejected all offers that he presented before him when he gone hastinapur for negotiations.
Pandavas also said that duryodhana has to pay for his sins and it's going to happen in the war. Bhim stood before karna and said that he is very lucky as he surrended before war or else he would also been killed like the kauravas.
Arjuna asked karna why he wanted to fight even from their side, when he has now the option of not participating in war. Karna said that it's krishna's order which he wanted to follow. Krishna agreed that they need karna as the opponents are way too powerful to be defeated easily.
Before everyone reach the camp, Krishna reminded karna about the boon he told him to ask; karna asks Krishna to be his charioteer in the war and a guide in his life. Arjuna stared at krishna not able to admit the fact that how karna won krishna's heart in a very short time. He doubts that krishna is now karn's friend.