Iraqi special forces are now less than 1.5km from the eastern outskirts of Mosul and are preparing to enter the city held by Islamic State fighters.
Hundreds of Counter-Terrorism Service (CTS) troops entered Bazwaya, the last village before the city limits, after launching a dawn assault on Monday.
A BBC correspondent travelling with them says there was some resistance, with car bombs targeting the convoy.
Units of the army’s ninth division are meanwhile advancing from the south.
Earlier, the military announced the start of an operation to retake the side of Mosul east of the River Tigris, which flows through the city.
Hundreds of troops in heavily-armoured Humvees, together with tanks and bulldozers, advanced on the village, supported by US-led coalition air strikes, our correspondent adds
Within hours the head of the Iraqi military’s Nineveh Operations Command, Lt-Gen Abdul Amir Yarallah, announced that they had entered Bazwaya and raised the Iraqi flag.
Our correspondent says that a column of troops is now probing different parts of Mosul’s outskirts, as commanders make a plan about where to go next.
When Daesh (a term for IS) entered Mosul, they killed my father because he was a police officer. I got away – they didn’t come after me.
My village was besieged for two years and a couple of months. If I had spoken to anyone about being in the police or army, Daesh would have killed me.
It happened to many of my close friends. They would go to their homes and Daesh would just take them away.
Daesh are just beards. They force you to attend all the prayers at the mosque. If your woman is not wearing a hijab, they will whip you – they have complete control.
One senior officer told the Associated Press news agency that they aimed to enter the city limits later on Monday, while another told Reuters they were already fighting in the Karama district.
CTS commander Lt Gen Abdul Wahhab al-Saidi denied that the troops had entered Karama. But he did say that they were moving on Kukjali, an industrial zone west of Bazwaya that lies about 1km from Mosul’s municipal boundary.