The 24-year old Japanese International has had few chances to play for the Red Devils since David Moyes took charge in July 2013.
This exclusion from the first team in the past 2 months is a surprise to many as he has the honour of being the first Asian player to score a hat-trick in the Premier League in a 4-0 home win against Norwich City in March 2013, and the first Japanese player to win a Premier League title.
At Old Trafford in the match against Real Sociedad, the former Dortmund player was given his first European start for United on the left wing.
Kagawa displayed an impressive performance on Wednesday, and was responsible for most of United's surge towards the Sociedad penalty box.
"I thought it was Shinji's best game in my time here," Moyes told the club's official website.
"He hadn't really found his feet yet but I saw something from Shinji which I hadn't seen in other games, so I was really pleased.
"His effort when we didn't have the ball was fantastic. With Shinji, everybody tells me about his ability and what he has got, but tonight is the first time I’ve really seen Shinji."
It was in the 80th minute of the match against Real Sociedad that the Japanese was shifted into his favourite No.10 position due to a Hernandez exit.
"I thought when we put him into the No.10 role, and even after it, he was good with Wayne. His attitude and energy were excellent and I was pleased for him." Moyes continued.
Kagawa officially joined Manchester United in 22 June 2012 after an agreement was reached with Borussia Dortmund, making him the first ever Japanese player to join the side at Old Trafford.