This victory, though, by three tries to two at home came at a cost, with flanker and captain Michael Hills possibly out until Christmas after suffering a nasty leg injury after only 23 minutes.
The Knights’ new fly-half, Tongan international Kurt Morath, who kicked a conversion and three penalties on his home Championship debut, was also injured as he required several stitches to the mouth.
After a mediocre first half in which Hartpury deservedly led 17-6, Doncaster’s forwards began to live up to their reputation.
Possession and territory were gained and the pressure forced Hartpury’s pack into errors that turned the contest.
Flanker Rob Langley received a yellow card on 45 minutes, but lessons weren’t learned because only three minutes later, Doncaster earned a breakthrough when they were awarded a penalty try following the collapse of a scrum.
The gap between the two sides was cut to only four points and with Hartpury not able to add to their earlier tries, Doncaster gradually became stronger.
The Knights, showing more confidence, then created an excellent move involving the pack and backs Morath and Tyson Lewis which resulted in full-back Cameron Cowell scoring, Morath converting to give the hosts a 20-17 lead.
Hartpury, though, were still dangerous opponents periodically, but on 78 minutes their enterprise proved fatal.
A long pass out to the wing was intercepted by three-quarter Steve McColl, who dashed more than 60 metres, unopposed, to score a thrilling try which stretched the lead to 28-17 and one that guaranteed victory.
Doncaster Knights: Cowell, McColl, Hayes, Matavesi, Lewis, Morath, James (Seniloli 78), Hislop (Williams 62), Hunter (Malcolm 72), Quigley (Sproston 53), Eames (Challinor 70), Hicks, Calladine, Hills (Tyrell 23), Ryan.
Hartpury: Foley, Sheldon (Chamberlain 58), Eves, Forrester, Henry, Cozens (Cochrane 67), Bolt, Murphy (Morris 47), Stratford (Tanner 53), Gibson (Merrey 50), Craig, Linsell, Langley, Gilbert (Pashley 62) Grieve.
Referee: John Meredith.