Grujic failed to secure a permanent switch away from Merseyside before the end of the English transfer window, but the Portuguese deadline was extended to October 25.
It will be Grujic’s fifth loan move since arriving at Liverpool in 2016, having spent time back with Red Star Belgrade, before a half-season with Cardiff and two successive campaigns at Hertha Berlin.
Moving to Portugal is a departure for the 24-year-old, but the prospect of a regular starting role under Sergio Conceicao is an appealing one.
But with eight senior midfielders ahead of him in the pecking order, and 18 non-homegrown players fighting for 17 spots in the Premier League squad, a departure was a sensible course of action.
Now, he will be looking to impress with his performances for a side battling for the Primeira Liga title, as well as competing in the Champions League.
All the best, Marko!