Macheda was allowed to leave United on loan for the rest of the season in order to get regular first-team football.
The Italy Under 21 forward told Gazzetta dello Sport: “There are still a couple of faxes (to be sent) but sometime between Wednesday and Thursday I will be in Italy.
“I am only playing 10-20 minute spells in games currently and that is not helping my growth. Ferguson is of the same opinion.
“In this regard, we are all happy because in six months’ time, Manchester United will get a stronger player.
“I’m happy to go to Sampdoria. Genoa is a beautiful city and I am happy.
“Sampdoria was the club which really tried to take me. With Lazio, there was never anything concrete.
“I need to play regularly and I think this is the best choice, but nobody has assured me a place. I’ll have to earn it.
“In Manchester, there was too much competition. Ferguson is a teacher, the best coach in the world and I’m sorry to leave him, even for a short period, but he also encouraged me to take this new experience.”