The Japan star became the first Asian player to score a treble in the Barclays Premier League as he launched United towards a 4-0 win over Norwich at Old Trafford. It was the stand-out contribution to what was largely a drab affair and enough to take United 15 points clear of Manchester City in the title race.
"It was a brilliant day for him," said Ferguson. "He is a good finisher. His second goal was composed and intelligent, his last was brilliant."
Ferguson feels there is much more to come from Kagawa, whose only other goals this term came prior to a knee injury sustained against Braga in October that kept him out for over two months and hampered progress following a summer move from Borussia Dortmund.
"He missed that period of football in October and November that set him back a bit," Ferguson added. "He is gradually getting his form back but next year he will be far better, you will see a really good player then."
Strangely, Kagawa's heroics may not be enough to get him a starting berth against Real Madrid on Tuesday. Rio Ferdinand and Rafael were left out with that game in mind, whilst Ryan Giggs was also denied a 1,000th senior appearance in readiness for some meaningful contribution against Jose Mourinho's men.
Nevertheless, Norwich could feel somewhat aggrieved at the final scoreline given they were only a goal down heading into the last 20 minutes, with United barely getting out of second gear.
It was then that Wayne Rooney made his decisive contribution, setting up two for Kagawa before belting home his 14th of the season in the final minute. "It was good to get Wayne the full game," said Ferguson. "He scored a goal, which is always important for a striker. It will help his confidence."
Norwich boss Chris Hughton believes United will progress in Europe, just as he thinks - with 10 games remaining - the Red Devils are now sauntering towards a record 20th championship.
"What you have with United is a team that is playing well enough," he said. "If you look at their recent run, they are winning games comfortably. At the moment you don't see any other outcome than them winning the title. Offensively, when they are at their best, United are outstanding."
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