"It's the decider," he said. "If we lose this match we should prepare for the play-offs because it will be too big a gap then.
"Scunthorpe have drawn a couple lately, but they are still unbeaten and I can't really see them blowing up. If Bristol beat us then they will go up as well.
"There is a lot of pressure on the match. This is our cup final. We have to go down there and get the win. A draw wouldn't be bad, but that still wouldn't close the gap."
After their uncertain form since the turn of the year Colin Calderwood's men are finally looking like finding some consistency in the final weeks of the season - and Tyson believes that is only going to pile the pressure on Bristol.
"Neither of us can slip up now - especially us," said the £675,000 striker. "Like last year we are chasing, which is not bad because they've always got to look over their shoulder."