After the successful assassination of Vaskar Pandit and other Maratha commanders, Alibordi returned to Murshidabad. He distributed one million rupees among the soldiers as reward and assured his main commanders of higher position. At that time, Alibordi's elder brother Haji Ahmad, being annoyed with his brother for not making him the fauzdar ( police chief ) of Hooghly went to Patna. On the other hand, Alibordi promised his chief commander Mustafa Khan the power of Bihar. At that time, Bihar's ruler was Siraj ud Daulah's father Zain Uddin. Alibordi was unwilling to fire his son-in-law to hand over Bihar's power to Mustafa Khan. But Mustafa created pressure on Alibordi to keep his promise. He wanted the post as if he was a partner in Alibordi's supremacy, not an employee. Alibordi realized that he was gradually becoming his commanders’ toy. Mustafa Khan became so influential that when the tax collectors fined the Zamindars or took other legal steps to collect revenues, the Zamindars bribed Mustafa instead and then they did not have to pay their revenues. Even the Nawab's dewani employees were not that powerful to the subjects as Mustafa Khan. Alibordi became agitated for Mustofa’s such behaviour. Alibordi’s agitation was that, if Mustofa was given the power to rule Bihar, he would grow more powerful and by dint of this growing power he would declare war against Alibordi Khan as Alibordi Khan did against Sarfaraz Khan. Alibordi Khan tried to make Mustafa understand in many ways that he would not be made the ruler of Bihar, but Mustafa was determined to be so. As a result, they become malicious of each other. Each of them began to move with extra protection in fear of assassination. After a few days, Alibordi invited Mustafa to his court. Mustafa set out for the royal court along with his companions and soldiers. Suddenly news came out that Alibordi's wife was feeling unwell. So she wanted to see Alibordi. At that moment hearing sounds of people's footsteps in the inner apartments of the house, Mustafa became frightened and took shelter in the shed outside. On the other hand, Alibordi sent Nawazesh Muhammad to Mustafa with the message that the Nawab was waiting to meet Mustafa. Mustafa inquired about the sudden departure of the Nawab. Nawazesh informed him about the situation, but Mustafa refused to meet with the Nawab and declared that he would not work under Alibordi anymore. Besides, he asked to pay off his salary as well as the soldiers’ working under him. Alibordi agreed with his proposal and easily gave him 1700,000 rupees. Then Alibordi ordered Mustafa to leave his territory. Nawab Alibordi's behavior made Mustafa think that Alibordi was weak and afraid. So the venturous Mustafa proposed the Afgan commanders that they should dethrone Alibordi and divide his territory among themselves equally. An Afgan commander named Samsher Khan agreed to his proposal, but other commanders including Sardar Khan and Rahim Khan disagreed. They said that they would agree to Mustafa's proposal if the Nawab didn't pay their owing and that rebellion without a cause would be ingratitude and iniquitous. After failing to make them rebellious, Mustafa set out to occupy Bihar with 8,000 cavalry and many infantry soldiers.
When Alibordi heard this, he ordered Zain Uddin to leave Bihar. Alibordi along with his loyal commanders and soldiers set out to suppress Mustafa Khan. On the other hand , Mustafa seized some elephants and cannons after plundering Rajmahal and went to Munger from there. Then he advanced towards Patna. He thought that he would easily occupy Patna. But disobeying Alibordi’s order, Zain Uddin set up camp with his soldiers and sent a messenger to know Mustafa's intention. He also sent the message that Mustafa must show the nawab's order letter if he wanted to take Bihar, or if he wanted to go to Ajodhya through this province then he could take any road outside of the capital. Mustafa replied,"a valiant victorious does not need permission paper from the emperor to conquer a state." Mustafa also asked, "on whose permission did Alibordi occupy Bengal and Kill our supreme leader (Sarfaraz)?"
Without being afraid of the rebels’ advancement, Zain Uddin decided to obstruct their movement. There were 6,000 cavalry among his soldiers and most of his soldiers were experienced. But when Mustafa Khan attacked Zain Uddin's camp, the soldiers began to flee in fear. A few thousand soldiers were busy to protect Zain Uddin. When Mustafa's elephant rider was killed by a bullet, the elephant became unruly. Failed to control the elephant, Mustafa mounted a horse. On the other hand, Mustafa's soldiers thought he was dead as they did not see him. They gave up fighting and began to flee towards their camp in fear. After failing to assemble them, Mustafa himself went back to the camp. After that, skirmishes went on for six days. On the eighth day, Mustafa attacked with his battle-ready force. But unfortunately for him, an arrow struck him in the eye in the early stage of the battle and he was forced to run away.
In the meantime, Alibordi arrived in Patna with his enormous army. Hearing this news Mustafa gave up his hope of occupying Patna and began to run off towards the border. Nawab Alibordi and his son-in-law Zain Uddin's joint force drove Mustafa's force out from one place to another. At one stage, Mustafa saw his chance of winning if the Marathas joined him. But when two of his main commanders were killed, he gave up fighting and entered Ajodhya to take shelter in the Chunar fort. As Alibordi had a dispute with Ajodhya's Nawab Safdar Jong, he gave up chasing Mustafa Khan and returned to Patna.