Adnan Januzaj believes Louis van Gaal preferred to buy £100m players rather than giving him a chance at Manchester United, as the Belgian prepares to face his first club in the Europa League.

Januzaj's Real Sociedad face United at Juventus' Allianz Stadium in the last-32 first leg on Thursday.

The winger, 26, left United for the La Liga club in 2017.

"Van Gaal wanted experienced players, he wanted to buy a player for £100m," Januzaj told BBC Sport.

Januzaj - who joined United's youth team in 2011 as a 16-year-old - broke into the first team and became a regular under David Moyes in 2013-14, making his debut in the Community Shield.

At that stage he looked destined to become a star for United. He was nominated for BBC Young Sports Personality of the Year, signed a five-year deal and England were interested in calling him up if he lived in the country long enough to earn residency.

He went to the World Cup that summer, as an 18-year-old, with Belgium.

Then United appointed Van Gaal as manager in 2014.

"All I needed was a coach to believe in me," said Januzaj. "After Moyes left, it was difficult because I was not playing a lot. I was playing one game, then staying on the bench, then another game, then six on the bench.

"As a young boy who wanted to play it was difficult for me to stay on the bench and not show people how good I was.

"I had those three coaches [reserve boss Warren Joyce, Sir Alex Ferguson and Moyes] giving me a lift to play for the club I love. Then those people came."

Januzaj only made nine Premier League starts under Van Gaal. Loan spells at Borussia Dortmund and Moyes' Sunderland failed to revitalise his career.

Things got worse when Jose Mourinho arrived at United in 2016 and took the number 11 shirt off Januzaj.

"The only thing I regret is at 19 when Van Gaal came was [I should have tried to] leave the club, to go and enjoy my football somewhere else," he said.

"They didn't want to let me go, they wanted me to go on loan. It's difficult to go somewhere on loan."

Januzaj - who says he is "in the best moment of my career" - is looking forward to seeing "close friend" Paul Pogba, who he speaks to several times a week.

"He's one of the kindest guys you'd ever meet," he said. "He's always happy and making people happy, always with a smile on his face. It's important to have people like him around the club.

"It's amazing to go back to the team I love, the team I did all my classes at. I have so many friends there but once you're on the pitch there's no friends."

Real Sociedad have effectively lost home advantage for the first leg, because Spain has placed restrictions on travellers from the UK, so the game will be played in Italy.

Januzaj says "it's not a big problem" because they would not have had fans anyway.

"It will be amazing [going back to Old Trafford for the second leg next Thursday]. The people in the city are amazing. I really like to go back to England a lot.

"To go back where I started my career will be an amazing feeling."