Jonjo Shelvey says Newcastle United's players must "realise the situation we're in" – before it's too late.
The winless club is second-bottom of the Premier League with eight games played.
Manchester United came from two goals down to beat Rafa Benitez's side 3-2 at Old Trafford on Saturday.
Newcastle were the better team for 45 minutes, but a 70th-minute free-kick from Juan Mata sparked a comeback from the home team.
"We can't keep putting it off saying 'next week, next week', we've got to realise the situation we're in," said midfielder Shelvey.
"These next 10 games are massive. We need to realise the situation we're in and really put our feet to the metal and work hard on the training pitch. That's the only way we're going to get out of this - by sticking together and keeping this unity going.
"We've got a great squad, we just need to start turning these performances into results."
United because to address their position until the October 20 home game against Brighton and Hove Albion because of the two-week international break.
Shelvey was again overlooked by England manager Gareth Southgate.
"For me, I think it's the worst thing that could happen," Shelvey told NUFC TV. "You're going into the international break knowing you've not got a game for two weeks.
"This game will be getting replayed and replayed in your head.
"For me, personally, it's going to be bad thing, because you're going to be thinking about it over and over again.
"But it is what it is. It's time to get back on to the training pitch and work our socks off."
Newcastle led 2-0 at Old Trafford with just 10 minutes gone thanks to goals from Kenedy and Yoshinori Muto.
However, United, denied a blatant penalty in the first half, couldn't get what would have been a decisive third goal.
"It's not a good place to be in the dressing room at the minute," said Shelvey after the game. "It just feels a bit gutting that we performed so well in the first half, and created all those chances. If we'd have been 3-0 up, you could see us holding out towards the end.
"But I think 2-0 is always a dangerous scoreline."