The Japan international midfielder was rotated in and out of the Red Devils side last season, partly due to injuries, as they charged towards their 13th Premier League title.
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"I wasn't satisfied with my overall performance but I played well in the second half of the season and started to get more and more confidence," Kagawa told Sports Illustrated.
"Hopefully, I can keep that going at the Confederations Cup.
"In this business, you need to be like Wayne Rooney or Robin van Persie and prove yourself if you want the ball. I want to be a player like them, which means I need results."
The former Borussia Dortmund midfielder made 26 appearances in his first season at Old Trafford, finding the back of the net six times.