Arjen Robben is convinced Louis van Gaal will lead United straight back into the Champions League.

The Dutch winger, who worked under Van Gaal at Bayern Munich and with the Holland national squad, believes the 63-year-old can bring the good times back to Old Trafford.

But he also urged caution – adding that it will take time for his compatriot to make his mark on his new club.

United slumped to a seventh place finish in the Premier League last season as David Moyes’ reign was short after just nine months.

Robben was among the players Van Gaal targeted when appointed by Ed Woodward, only for the ex-Chelsea player to opt to stay at Bayern.

United went on to spend over £150m on Angel di Maria, Radamel Falcao, Ander Herrera, Luke Shaw, Marcos Rojo and Daley Blind as American owners the Glazer family underlined their intention to return to the summit of English football.

But it has been a disappointing start to the campaign, with Van Gaal having to wait until last weekend’s 4-0 win against QPR to collect his first victory of the season.

Robben believes that will be a springboard for his former manager.

He said: “I haven’t spoken to him recently, but I was very happy for him that he won the game against QPR.

“Hopefully now he can show that he will do very well, but he needs time.

“I know how it works – if you are not winning, you get the pressure but the management at United know what sort of coach they have got and I am very confident he will be successful there.

“He will get United back into the Champions League next season, where they belong.

“They are such a big club and that is where they belong.”

United executive vice chairman Woodward went in pursuit of a proven winner following Moyes’ disastrous reign.

Van Gaal fits that bill having won titles with every club he has managed, as well as leading Holland to the semi finals of World Cup in Brazil.

United’s willingness to back him so heavily in the transfer market, as well as sanction the sales of youth products Danny Welbeck and Tom Cleverley is evidence of their faith in the former Ajax and Barcelona coach’s methods.

Those departures, coupled with United’s lavish spending, led to accusations that the club had abandoned a commitment to youth that was the cornerstone of the successes enjoyed by Sir Matt Busby and Sir Alex Ferguson.

Ferguson’s former assistant Mike Phelan claimed part of United had lost part of their identity when agreeing to sell Welbeck to title rivals Arsenal for £16m on transfer deadline day.

Phelan said: “Danny Welbeck has been part of United’s identity and that has been broken.

“What will happen in the future now, nobody knows but that thread has been broken now.”

But Robben, who was at Bayern when Van Gaal gave young players like Thomas Muller the chance to shine at the Allianz Arena, believes his compatriot will bring on a new generation of stars at Old Trafford.

“I have worked with Van Gaal at Bayern as well as with Holland, so I have known him for a very long time,” he said.

“He is one of the few coaches, I think, who can make teams play better. He makes players better. United have some young, talented players and I have no doubts that he will do well at Old Trafford.”