Moyes appeared to show a lack of faith in Japan star Kagawa.
After starting him on the left-hand side of midfield, Kagawa was then hauled off at half-time, replaced by 18-year-old Adnan Januzaj.
"I just decided I wanted to make a change and inject a little bit of something," said Moyes. "Adnan showed what he can do in periods.
"We want Shinji to feel he's getting an opportunity to show what he can do and his best position may be number 10.
"But even for Japan he plays off the left as well so it's not something which is strange to him or a position he's not used to.
"There's a lot of competition here and we want to push each other."
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