The Qur'an says (39:5)

[God] wraps the night into the day and the day into the night.

The word used here, كور incidentally has the same root as ball but that is not necessary here for this argument.

The problem is we aren't tracking the sun in this verse, we are tracking "day" and "night" this is a subtle and important difference.

27:86 of the Qur'an defines day by saying

Do they not see that We made the night that they may rest therein and the day giving sight? Indeed in that are signs for a people who believe.

and 10:67

It is He who made for you the night to rest therein and the day, giving sight. Indeed in that are signs for a people who listen.

Ibn Kathir say

He it is Who has appointed for you the night that you may rest therein, and the day to make things visible (to you). Allah informed us that He is the One Who made the night for His servants to rest therein from weariness and exhaustion. And the day to make things visible (to you). bright and clear for them to seek livelihood and to travel to fulfill their needs.

The day was made by God for man to see and go out and do stuff. G

Imagine the Earth was flat with some determined width. When the sun is on the width, is it day time there? Well 39:5 says yes, as the wrapping is continuous.

The only way you can have continuous day time, where people are going about traveling and fulfilling their needs is on a spherical earth. On a flat earth, day time would transiently end at the edges, which is not consistent with a wrapping of daily events.