Although the Reds won the contest 3-0, seeing their main striker stretchered off the pitch tarnished the result somewhat and it seems that he could be set for a lengthy lay off.
The former Peterborough United forward has scored the bulk of the Reds' goals this campaign, but his absence could be good news for one member of the squad.
Although no player would ever want to see their teammate ruled out through injury, Lars Veldwijk will feel that now is the chance for him to prove his worth.
Veldwijk was brought in by Forest last summer, but he has failed to make any sort of impression during his time at the club so far.
The Dutchman has played just 10 times since moving to the City Ground, with his performances casting doubts over whether he has the quality to function in England's second-tier.
Veldwijk has still not hit the back of the net, but he could be in-line to receive more regular action with Assombalonga sidelined and will be hoping to convince Dougie Freedman that he has a part to play.
The 23-year-old will be in competition for a place with Matty Fryatt and Dexter Blackstock, but should feel he has a decent chance of dislodging either of the front-men - with the pair both struggling for goals this season.
If Veldwijk can seize his opportunity, he may start to pay back some of his transfer fee and erase any doubts that have emerged over his future after his poor start to life with the Reds.