Mixu Paatelainen admits Dundee United will face an immense task to avoid relegation if his side lose at home to Kilmarnock on Saturday.
The Tannadice side are 14 points adrift of Killie, Hamilton and Partick Thistle at the bottom of the Premiership.
"Obviously, if we don't win tomorrow, it will be very difficult for us," said manager Paatelainen.
"Mathematically, it will still be possible, but we do realise the situation and how big the match is."
Paatelainen took over from Jackie McNamara in October and the team have gathered only five points from a total of 36 since.
Kilmarnock, meanwhile, arrive after an upturn in their own form that has led to three games without defeat and two consecutive wins.
"Tomorrow's match is a huge one," said Paatelainen. "There is no question about that. No one is shying away from that."
The Finn says the job of keeping the club in the Premiership is the most difficult in his managerial career.
He insists that, if he were to help United beat the drop, it would be his greatest feat as a team boss.
"It would be unbelievable, because of where we are, the changes we had to make, the information to players that we had to put in," he said.
"For all of us, it would be an unbelievable achievement because the situation is not good at all.
"We do feel it is still possible and we are fighting. We will do everything possible tomorrow to win the match and start climbing."
United players, led by captain Sean Dillon, held a meeting earlier this week in a bid to address their slump in form.
Experienced midfielder John Rankin said the meeting brought out some home truths.
"We aired a few grievances and it's one that probably we needed and, to be honest, we probably needed it earlier on in the season, but it never came about," he said.
"Sean took responsibility. He is the club captain and a few players aired what they thought.
"Training this week has been at a different tempo, a different standard from the few weeks before."
Rankin said a "few arguments" left a few players "battered and bruised" but said that was to be expected "as the pressure is on".
"In terms of my Dundee United career, this is probably the biggest game I will have played in," he said of Kilmarnock's visit.
"I have played in European ties and I have played in cup finals, but this is bigger than any cup final I have played in."