The Knights were a shadow of the side that defeated local rivals Yorkshire Carnegie in the semi-finals as they fell to a 28-13 defeat at Castle Park.
“We defended really well but we didn’t get the chance to impose our game on Bristol which we were really frustrated with and that’s something we are looking to rectify on Wednesday,” the second-row told TRP.
“We coughed the ball up too easily and that invited pressure on ourselves.”
Doncaster need to better the 12-point win they managed at Bristol back in November if they are to go up.
“When they got their third try our heads could easily have gone down and we could have started feeling sorry for ourselves. But the subs that came on made a big difference,” the 32-year-old said.
“Yes, we are 15 points behind but we still fancy ourselves – that’s the nature of this team. We know if we get the rub of the green and impose our game we’ll have an outside chance.
“When we keep the ball through multiple phases we threaten teams because we have lots of different avenues to go down in terms of our attack: we have a strong driving lineout, we have a powerful forward game and we’ve got slick backs.”
Wednesday’s second leg could be the last game of the current play-off system.
Talks are currently taking place with Premiership Rugby Limited (PRL) about reverting to a straight one-up, one-down system or reintroducing a play-off between the bottom-placed Premiership team and the top Championship team at the end of the regular season.
It is believed that the latter scenario would come with a £40,000 pay out from PRL to each of the Championship clubs.
“I don’t think you’d see many Championship teams beat a full Premiership team, the odds would be stacked against them because of the big gap in funding the calibre of player they’re able to attract,” Challinor said.
“Obviously we’re not complaining about the play-offs but I do think the team that finishes top, as Bristol have done on three or four occasions, should go up automatically.”
JON NEWCOMBE