Manchester United manager Louis van Gaal has calmed fears over Angel di Maria's continued fitness problems after the Argentina international was being substituted with cramp during the 4-0 win over Queens Park Rangers on Sunday.

Di Maria produced a man of the match performance on his home debut, scoring once and making another as United secured their first win of the season with an emphatic win against Harry Redknapp's beleaguered QPR.

But just like against Burnley, the scene of Di Maria's first appearance for United, the British record signing went off with a bout of cramp late on, leading to fears over his fitness during the early weeks of the campaign.

However, Van Gaal said: "Di Maria is all right. Di Maria has never played 90 minutes until now in his pre-season and season. He has cramp and normally you have to play 90 minutes without cramp but that is also a positive signal. He gave everything."

The 26-year-old was replaced by Adnan Januzaj for the final eight minutes at Old Trafford but is not expected to be absent for United's visit to Leicester City next weekend.

As one of four home debutants alongside Daley Blind, Marcos Rojo and Radamel Falcao, Di Maria began repaying United's £59.7m summer investment with a stellar showing to kick-start Van Gaal's tenure at the club.

However van Gaal believes Di Maria can continue to improve.

"When you prepare three goals and make the first goal by yourself then you cannot play bad but he had a lot of unnecessary losses [of possession] so we can do better, even Angel Di Maria," the ex-Netherlands coach said.

"Can you do it better when you prepare three goals and make one? It is nearly impossible but I am analysing the game and I see things we can improve as a team."