Chris Smalling admitted on Saturday that struggling Manchester United were utterly frustrated by their failure to beat lowly Crystal Palace.

United are languishing off the pace in the battle to finish in the Premier League’s top four after their latest setback in a difficult season.

After losing to arch rivals Manchester City before the international break, Jose Mourinho’s team returned to action in forgettable fashion on Saturday.

Palace secured a 0-0 draw at Old Trafford with a composed display that neutralised United.

Angry United fans booed the players at full-time and Mourinho accused his team of lacking heart.

“I think we knew the sort of the period we had all the way to Christmas, there were so many home games that three points had to be a must,” United defender Smalling said.

“So, whether it was a point or no points, it just might as well have been a loss.

“I think it’s just about getting that first goal and then it sort of unlocks people and it makes them become a bit more open.

“Yeah, just utter frustration.”

Smalling knows it could have been even worse for United.

Patrick van Aanholt and Andros Townsend wasted glorious chances for Palace either side of half-time.

Smalling was guilty of wasting a fine chance from a free-kick in the first half, and a disappointing afternoon for the home side was summed up by out-of-form Romelu Lukaku seeing a goal ruled for offside.

“I think when it’s going against you, you don’t get those decisions,” Smalling said.

“But we’ll work hard again because we know, given this run, that we can’t have any more slip-ups at home again like this.

“I think we need to keep working hard as a team and creating those chances and ultimately finishing them and making sure the games that we are dominate we win.”

Young Boys head to Manchester for a vital Champions League group stage tie on Tuesday and Smalling demanded United deliver a far more focused effort.

“I thought the last 10 minutes there was added intensity that we maybe needed a bit earlier in the game,” Smalling told MUTV.

“But we can’t always leave it to the last minute and we needed to get that goal earlier.

“It is good to get back out in front of this crowd again (on Tuesday) and show a better performance.”