If the deadline is flexible, you could solve this problem by changing the deadline, and having the project finish later. This means he’s spending less time on the project each day. 

Since Aurif is working on a 40-hour project for the first two weeks, we need to extend his 80-hour project out quite a bit. Now he won’t deliver this design work until 16 March, when previously he was going to deliver it on 2 March. This may be fine if your client is flexible or the deadline is sufficiently far away. 

 How to extend a deadline:

1.  Click the right-hand side of the rectangle associated with the job, in Schedule mode or Assign mode. 

2.  Drag it to the right, until you reach your later deadline.