Forest swooped to land Assombalonga from Peterborough United back in the summer of 2014, forking out a fee of £5.5m according to BBC Sport.
Having hit 33 goals in just 58 games for Peterborough, Assombalonga arrived at the City Ground with high hopes, and after 15 goals in 32 games for Forest, he seemed to be on his way to stardom, before a major knee injury sustained in February 2015 kept him out of action for more than a year.
Now back in action, Assombalonga is set for a big season for Forest - but Philippe Montanier's men are having to fend off considerable interest in their 23-year-old striker.
The Daily Mail report that Norwich City have submitted a bid of £7m for Assombalonga as they look to return to the Premier League at the first time of asking - but Forest have rejected the offer.
The Canaries are searching for a new striker following their relegation, and their huge offer for Assombalonga suggests they have cash to spend this summer, but so far they haven't been able to tempt Forest into selling their star striker.
It's stated that Forest are looking at Genk striker Nikos Karelis, who would cost around £6m, as a potential replacement should Norwich - or any other team - lodge an acceptable bid for Assombalonga.
It now remains to be seen whether Alex Neil's side make another bid for Assombalonga, but so far, Forest are standing strong and snubbing interest - which will no doubt delight Forest fans who saw Michail Antonio leave for West Ham Untied last summer.
Do you think Assombalonga will leave Forest this summer?