Adnan Januzaj says he will dedicate his first goal for new club Real Sociedad to his former Manchester United coach Louis van Gaal, with whom he had a difficult working relationship.

Januzaj, 22, moved to La Liga from the Premier League last month in a reported £8 million transfer, with United including a buy-back clause for the player in the deal.

The Belgium international winger believes Spain is the ideal place for him to showcase his talent after struggling to hold down a regular first-team spot at Old Trafford, especially under Van Gaal.

"If I score a goal I will dedicate it to Van Gaal," Januzaj told AS. "I don't want to talk about him [Van Gaal] but everyone knows how many problems I had with him. We didn't have the best of rapports. It wasn't easy, it's very frustrating and difficult when you are in a situation like that."

Januzaj was a star of the youth and reserve teams at United and the 2013 reserve team player of the year. He featured in 38 games in all competitions, scoring five goals and setting up eight more in his breakthrough season under David Moyes in 2013-14.

"I thought he was one of the finest young talents I have ever seen, and he was up there with Wayne Rooney at the age of 18," Moyes later said of Januzaj.

Moyes' successor Van Gaal gave Januzaj chances to play early on but eventually dropped him and the player then saw his minutes cut by half from one season to the next. He was eventually loaned to Borussia Dortmund for the first half of the 2015-16 season.

"I didn't have many possibilities to play," he said. "I spent a long time on the bench and that makes you lose confidence and minor injuries emerge.

"Many times I wouldn't play as a starter and you struggle to shine without continuity. The coach would put me in positions that I didn't know how to play in and I had little experience in. I hope that one day, I can shut up all those people that criticised me."

Adnan Januzaj was sent on loan to Sunderland by Jose Mourinho. Getty

Januzaj did preseason training under new coach Jose Mourinho last summer before being sent out on a season-long loan to Sunderland, where he made 27 Premier League appearances, including 18 as a starter.

Despite failing to break into the United team under Mourinho he bears no grudge against the current United boss.

"I have nothing bad to say about Mourinho," he said. "I have no criticism of him as a coach. From the beginning he was fair."

Januzaj believes Real Sociedad is the ideal place to showcase his talent.

"I want to prove that I'm a good player," he said. "There have been comments made regarding my past performances and whether I could fulfil expectations that were placed on me.

"I'm young and I have the quality to play good football. I'm a player with a lot of experience compared to other players of my age. I've been able to play in big clubs, in very strong leagues, in the national team.

"What I want is to play football and here at La Real, I will be able to."

A strong season for La Real could see Januzaj contend for a spot in Belgium's World Cup squad next year.

A member of Belgium's 2014 World Cup that reached the quarterfinals, Januzaj says he is not thinking about that.

"It's not a priority," he said. "I already played at a World Cup at 18 and I know what that is like.

"My aim is to grow as a player and if the Belgium coach [Roberto Martinez] thinks I'm ready and calls me up, then I will be delighted."

Januzaj could make his La Liga debut in Friday's home game against Villarreal.