The 18-year-old scored twice during his senior debut for United - a 5-1 victory over FC Midtjylland in the Europa League - before following that up with another double in his first Premier League outing, a 3-2 victory over Arsenal.
Macheda similarly burst onto the scene after scoring a late winner against Aston Villa in 2009 but the striker failed to secure a regular role at Old Trafford and has ended up at Championship side Cardiff City following five loan spells.
“Marcus needs to continue working hard, don’t grow a big head, don’t read or listen to all the hype and be lucky with injuries,” the Italian striker told The Sun.
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“The kid has got a great chance to play more than I had, so he must stay as calm and hungry as he is now.
“United will look after him — so everything is stacked in his favour.”