An early score for Hartpury’s Mike Wilcox was followed by a swift response by Ben Hunter from an attacking lineout as the two sides set the tone for the game with an attacking start.
Josh Tyrell then scored his first try for the Knights off the back of another lineout before Harry Cochrane exploited sloppy play by the hosts to level the scores at 12.
A sumptuous chip from Jacob Perry found Luke Eves to score Hartpury’s third but then Andy Bulumaku and Michael Hills scored tries to give Doncaster a 24-17 lead and the try bonus.
After Hunter stretched the lead further it looked like Hartpury’s resistance might finally be broken but they struck back through Steven Leonard.
Lewis and the College men’s Darren Dawidiuk traded tries before the Knights finally pulled away with scores from Adam Batt and Tom James, the latter a beauty, to pull 17 points clear, even though Hartpury had the last word of a crazy game through Tom Seabrook.
Rotherham Titans’ relegation from the Championship will be confirmed in two weeks’ time if they lose to second-placed Ealing Trailfinders and London Scottish – who are 20 points clear with 30 points left to play for – pick up all five points at Hartpury.
Rotherham did manage to pick up another losing bonus point in an 18-15 defeat to Bedford Blues.
The Titans were 15-0 down and seemingly headed for another heavy defeat until tries from Rhodri Davies and Jake Henry pulled them level at 15-15, only for there to be a final twist as Will Hooley kicked a penalty in front of the sticks to win it for Bedford in added time.