Paddy McNair
McNair made up part of a make-shift United back-four which kept Arsenal at bay for long periods on Saturday.Getty Images

Manchester United manager Louis van Gaal has warned the club's rivals that young players Paddy McNair and Tyler Blackett among others have room for improvement despite both playing a leading role in the shock win over Arsenal.

Injuries has forced Van Gaal into blooding both McNair, 19, and Blackett, 20, this season, while Luke Shaw and Chris Smalling made up an inexperienced defence at the Emirates Stadium which kept the Gunners at bay for long periods.

Arsenal defender Kieran Gibbs' own goal and Wayne Rooney's breakaway strike handed United their first away win of the season but the showing of their young players underpinned the victory in north London and Van Gaal says the quartet can get better still.

"You can say, when you play with this squad, with players like Paddy McNair and Tyler Blackett and also Luke Shaw - 19, 20, 21 [years old] - and Smalling between them, you can after the match it was good," he said. "But they can do better, I believe."

McNair was handed his United debut in the win over West Ham United in September and has gone on to make five appearances this season, while Blackett was involved in the opening day loss to Swansea City and has featured on seven occasions this term.

Despite victory over Arsenal taking United back into the top four, Van Gaal is unwilling to rest on his laurels during the early months of his reign at Old Trafford and demands further progress after seeing Arsene Wenger's side dominate for large periods on Saturday 22 November.

"The first 20 to 25 minutes I was a little disappointed about our confidence on the ball, our composure at the ball," he added.

"That was our biggest problem. That's why Arsenal could develop this storm. But we have a very good goalkeeper.

"But after 25 minutes I saw that when we keep the ball that's when we get chances. I said at half-time 'you need a little bit more confidence, play the ball' and because we keep the ball better in the second half we created those chances."