Manchester - Manchester United manager Louis van Gaal believes it would be a major disappointment if his side are unable to escape "the rat race" and secure a return to the Champions League.
The Red Devils currently occupy fourth place, a point of ahead of fifth-placed Southampton, ahead of their Premier League fixture against Sunderland.
However, just four points separate Arsenal in third with 48 points and Tottenham in seventh place with 44 points after 26 matches of the campaign.
And Van Gaal claims it is essential his side beat Sunderland at Old Trafford on Saturday to keep up the pressure on their top-four rivals.
"It is because of the rat race between five clubs that we have to win, we have to be there," Van Gaal said.
"It would be a big disappointment (not to make top four), of course, a big disappointment.
"When you start the season with objective of finishing in the first four of the league it is your objective and you are occupied with doing that. When I came here, that was my goal and we are still there.
"Therefore you have to win your matches because the other clubs are winning their matches."
Van Gaal has been satisfied with results United have produced recently, with last weekend's 2-1 loss to Swansea City only their second defeat in 20 league and cup matches.
But he believes there are still big improvements to be made in the performance levels of his players.
"I am pleased with the results, but not with a lot of the performances of my team," he said.
"Our process is continuing and always we are going better. In spite of the many injuries we have had in the first half of the season, we are there.
"Also in spite of the criticism of our defence, we are there, we don't have many goals against us.
"So, we are not unhappy. When you see our matches we are mostly the better team, but the better team is not always winning."
Ahead of the game against Sunderland, United midfielder Michael Carrick has resumed training following his recovery from a calf strain but is unlikely to be risked, while striker James Wilson has recovered from a dead leg.
The Red Devils are definitely without Netherlands striker Robin van Persie, who misses out with an ongoing ankle problem.
Van Gaal added: "He (Van Persie) is injured. The only injured player that I have. So, we change Carrick for Van Persie.
"Robin has an ankle problem so I don't think it is heavy, but an ankle problem takes a long time. It's not one or two weeks, but we will have to wait and see.
"Michael is very experienced and he can play in a very important position. But he also needs match rhythm.
"He trained only one time with us, with the group, so he needs to also play in the second team."
Van Gaal also revealed his happiness that young defenders Tyler Blackett and Reece James have both signed new long-term contracts to remain at Old Trafford.
"When I came here there they told me that they wanted to have more youth academy players in the first-team," he explained.
"I am happy that we can sign players from our youth academy and our players are very popular as we also have a lot of youngsters out on loan. I believe in players that you have educated in your own youth academy."