Leyton Orient manager Russell Slade now knows his side have a mountain to climb if they are to gatecrash their way into the play-offs after a costly 2-1 defeat at relegation-threatened Scunthorpe.
It was the first defeat in eight games for the Londoners, leaving them five points adrift of the top six.
Orient were punished for a sluggish start as Akpo Sodje and Niall Canavan steered Scunthorpe into a 2-0 lead in the opening 42 minutes.
Kevin Lisbie pulled a goal back on the stroke of half-time but after the interval Orient could not find a way past young keeper Eirik Holmen Johansen, on loan to the home side from Manchester City.
Slade said: "The mathematics are now simple. We have to win all our last five games if we are to make the play-offs.
"We have been on a really good run and to lose like this is difficult to take. We have created chances all afternoon but not taken enough of them.
"But we have left ourselves with a mountain to climb after starting so poorly."
For Scunthorpe boss Brian Laws, the result was a huge relief after four successive defeats.
He said: "We always knew this was a must-win game for us. To find ourselves out of the bottom four again at this stage of the season is a massive psychological boost for us.
"Our win has put pressure on the teams around us and it is now all about who holds their nerve in the closing few weeks of the season."