A nonplussed David de Gea believes Manchester United are enduring their "most difficult time" since his arrival in 2011.

The Red Devils suffered a third defeat in six Premier League matches on Sunday, as they went down 1-0 to Newcastle United at St James' Park.

Matty Longstaff's second-half strike proved the difference between the two sides, with Ole Gunnar Solskjaer's men mustering just three shots on target.

United, who have scored only twice in their past five games in all competitions and are enduring their worst start to a league season in 30 years, have still not won away from home since beating Paris Saint-Germain in March.

The initial upturn in results after Solskjaer replaced Jose Mourinho last December have long since subsided, and De Gea, who endured difficult times under David Moyes, Louis van Gaal and Mourinho, cannot remember a tougher period for the club.

Asked what was missing from their performance against Newcastle, De Gea told Sky Sports: "Everything. A lot of things to improve. They were the better team today.

"I don't know what to say, really. Just keep trying, fighting, improving every day. It's a hard moment for us.

"It's probably the most difficult time since I've been here. I don't know why, what is happening. We cannot score even one goal in two games.

"It's difficult to say something. Sorry to the fans. We will keep fighting for sure, we will come back, but at the moment we are in a difficult situation.

"We defended quite well. It's true they had good chances to score but, come one, we conceded a goal from our corner. That cannot happen.

"It's not acceptable, not just this game, the whole season. Keep fighting and see what happens in the next games."

United's next match is against arch-rivals Liverpool after the international break on October 20.