Greenberg lost his first bout against heavyweight contender Cedric Boswell (28–1; 22 KOs) in August 2008. He lost via TKO in the second round, after taking numerous punches from Boswell, who won for the 28th time in 29 fights, and is looking for a title bout opportunity. In June 2009, he was ranked 53rd in the International Boxing Organization's heavyweight computerized rankings. Of those ahead of him, only two were younger than he is. Greenberg has not fought in the ring after his loss to Boswell.