In 2009 he was the fresh faced supersub who curled in a stunner against Aston Villa at Old Trafford to win the game, and put United in control of the title race.
He followed it up with a winner at Sunderland, but since then regular appearances and goals have been hard to come by.
In a Tweet he has since deleted, he wrote: "Totally p****d off...this is not what i deserve! **** all!!!!!"
Before tweeting, "I'm gonna delete my Twitter! Take care u all."
He was expressing his feelings seemingly at being left out of QPR's 18 man squad to face Everton, although manager Mark Hughes attempted to make light of the situation suggesting the tweet could have been because he had broken a watch, before seriously saying he would have words with the Italian.
It is the second time in a week the young hothead has ended up in trouble via Twitter, days earlier charged by the FA for a homophobic remark.
Last season he was loaned to Sampdoria, scoring just one goal as they were relegated.
He returned to Manchester United where he ended up sixth choice striker this season, behind Wayne Rooney, Danny Welbeck, Javier Hernandez, Dimitar Berbatov and Michael Owen.
Of course it was Warnock who brought him to QPR, only to be sacked days later for Mark Hughes to bring in Djibril Cisse and Bobby Zamora in front of him.
But Cisse was suspended this weekend and Macheda still could not even get into the squad. Now after this Twitter outburst the future does not look bright for him.
Sir Alex Ferguson may let Owen and Berbatov go this summer, but it will be at his discretion whether Macheda is kept on.
He would have been looking for signs of progress on loan, similar to Danny Welbeck's performances for Sunderland last season.
Failing to break into the QPR squad does not bode well for him, and it may spell the end for his United career.
Will Federico Macheda ever make it at United or should they let him go?
image: © apasciuto