Manchester United midfielder Ander Herrerabelieves the team's top four hopes will hinge on the outcome of Thursday's derby against Manchester City.
United moved to within a point of City with Sunday's 2-0 victory at Burnley, which extended their unbeaten run in the league to 23 matches, and they will leapfrog their rivals if they win at the Etihad Stadium.
Herrera believes there is no margin for error. "It is going to be the game of the season," he said.
"We are one point behind them. If we win, we have the chance to finish in the top four, if they win it is going to be very difficult [for us]. Make or break? Probably. Both teams are in a good moment so if one of us wins the game we are not going to lose a lot of games, or make mistakes after that. It's us or them. It is going to be key.
"I don't know the winner takes all expression but it is going to be a massive game. We are in a very good moment, on a very good run and we respect them but we are doing a lot of good things and we have to show it on Thursday."
The Europa League represents an alternative route into next season's Champions League should United miss out on the top four and Herrera is desperate to atone for defeat with Athletic Bilbao in the final of the competition against Atletico Madrid in 2012. United face Celta Vigo in the first leg of their semi-final a week on Thursday.
"The Europa League is a competition that makes me very excited because I lost the final five years ago and I want to take that knife from my back," Herrera said.
"So hopefully we can fight for that title as well, but I know Celta Vigo very well. They are a very difficult team."
Meanwhile, Juan Mata is confident of shortly answering Jose Mourinho’s call to arms to his injured players.
Mata has been sidelined for the past 3½ weeks after undergoing hernia surgery but the United playmaker is hopeful of returning to action over the next fortnight as Mourinho prepares for a critical end to the season.
The first leg against Celta Vigo next Thursday and the trip to Arsenal three days later may come too soon but Mata hopes to make the second leg at home to the Spanish club on May 11.
"I’m feeling much better now and I hope to be back with the team soon, to try to help in the last spell of the season," Mata wrote in his blog, One Hour Behind.
"I hope so, because that’s all I want: being always available to help and to contribution as much as I can, both on and off the pitch. A million thanks for all your messages wishing me a speedy recovery, I’m getting closer!”
After the Burnley win, Mourinho had challenged the injured defensive pairing of Chris Smalling and Phil Jones to shun "safe thinking", adopt a "crazy mentality" and make "a last push" in order to return against City to ease the burden on Eric Bailly. Bailly is United’s only fit recognised centre-half with Marcos Rojo out for the rest of the season.