Haaland, who has seven goals in seven appearances so far for City, called to the bench to be substituted in the 67th minute of the Group A4 tie on Sunday night in what is a worry for City boss Enzo Maresca.
His limp comes ahead of vital fixtures against Liverpool and European champions Paris Saint-Germain, making life difficult for City as well as Fantasy Premier League owners as club football returns.
Currently, Haaland is owned by 73.9% of FPL players after picking up 39 points so far following 5 gameweeks. This makes him the striker with the most points as he leads Chelsea's Joao Pedro and Liverpool's Alexander Isak by a 6-point gap.
FPL players may have to take the risk and remove Haaland before City face Liverpool after the break, a move that may pay off if they bring in a differential over the 26-year-old who is in the majority of teams.
City were found guilty of more than 100 financial charges levelled against them by the Premier League and team morale will already be low heading into the Liverpool clash, where Haaland may miss out.
Maresca could face Liverpool and PSG without Haaland and with no real back up striker, City may start to collapse in what is going to be a long season for the club.