Iraq's special forces worked to fully push a fiercely resisting ISIL from neighbourhoods on Mosul's eastern edge while bombings killed at least 11 people elsewhere in the country.
The current phase and slower pace highlight the challenges ahead for Iraqi forces as they press into more populated areas deeper inside Mosul, where the civilian presence means they may not be able to rely as much on air raids.
"There are a lot of civilians and we are trying to protect them," said Lieutenant-Colonel Muhanad al-Timimi. "This is one of the hardest battles that we've faced."
Some civilians are fleeing the combat zone, while ISIL (also known as ISIS) fighters are holding others back for use as human shields, making it harder for Iraqi commanders on the ground to get approval for requests for US-led coalition bombing raids.
Iraqi forces first entered the eastern edge of the city on Tuesday.
On Friday, forces began pushing into Mosul proper, but so far have only advanced just over a kilometre into the city. On the city's southern front Iraqi forces are still some 20km from the city centre.
"Daesh dug trenches that they filled with water and they have a lot of suicide attackers and car bombs," said al-Timimi, using the Arabic acronym for the ISIL group.
At least 27 people were killed on Sunday in a series of suicide bombings carried out by ISIL across northern Iraq.
The deadliest attack took place in Tikrit, a city halfway between Baghdad and Mosul, where an ambulance packed with explosives went off at a security checkpoint, killing 15 people and injuring 35, a security official said.
The fighters fought back with ferocity on Saturday, pushing special forces from the southern edge of the Gogjali neighbourhood, where the troops had made their first major foray into the city itself after more than two weeks of fighting in its rural outskirts.
ISIL emerged from deeper in the city to target Iraqi soldiers with mortars and suicide car bombs. They also attacked the southern edge of the Gogjali district, which Iraqi forces declared "liberated" earlier this week, pushing back some gains.
|'The longer the battle to retake Mosul goes on, the more difficult it will become for the Iraqi forces' [Al Jazeera]
Al Jazeera's Jamal Elshayyal, reporting from a military camp near Bashiqa, northeast of Mosul, said while the momentum was with the anti-ISIL forces, it would become more difficult for the Iraqi army the longer this battle goes on.
"ISIL doesn't have a conventional army that can go into combat with the Iraqi forces," he said.
"So it works for them when they carry out suicide attacks, striking fear in the hearts of the people. The attacks also slow down the Iraqi army's advances. And it will add to the cost of the army.
"The longer the battle to retake Mosul goes on, the more difficult it will become for the Iraqi forces."
Both sides fired mortar rounds and automatic weapons, while the Iraqi troops also responded with artillery. Snipers duelled from rooftops in residential areas, where most buildings are just two storeys high.
Truckloads full of as many as 1,600 civilians may have been forcibly moved from Hammam al-Alil to Tal Afar earlier this week, and may be transferred onwards into Syria for possible use as human shields, the office of the UN High Commissioner for Human Rights warned on Friday.
Source: Al Jazeera News And Agencies