The former Villarreal and Fiorentina striker's career has been slowed by knee injuries and he has been out of contract since leaving Genoa at the end of last season. With Ole Gunnar Solskjaer now in charge temporarily of United, the 31-year-old Rossi has been invited back to Manchester by his former teammate to get his playing sharpness back.
"This just shows you how much of a family Manchester United is. They have always taken care of their players," Rossi said. "It's a real privilege to have this opportunity and be given this opportunity. It feels really good. When I heard about this opportunity it just brought so much joy.
"It's great to be playing with these exceptional players that I've been training with. It's helping me stay fit and stay sharp because if you're not sharp they'll definitely be on you. I make sure that I'm doing the best I can to better myself but also to help the team do the right things in training."
Rossi played for Italy from 2008-14. He needed four knee operations from October 2011 to September 2014. He was playing in Spain in 2016 when he tore the ACL in his left knee. Rossi joined Genoa in December 2017 on a free transfer and scored one goal in 10 matches over the second half of last season.
"I just love this game," Rossi said. "I sacrificed so much in these years, I've had many highs, I've had a few lows with these injuries that have taken a lot away from me, but I never stopped."
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