Knights scored three tries without reply in the second half to claim a 28-17 victory over a determined Hartpury side.
Hartpury had surprised Yorkshire Carnegie on the opening day of the season and must have fancied their chances of a first ever win at Castle Park when leading 17-6 at the end of a first half during which Knights had blown hot and cold.
Although Knights defended well, as they did in the second, their kicking game was poor at times and their new look half-back combination of Tom James and summer signing Kurt Morath didn't always gel, with the result that their three-quarter line had to live off scraps at times.
Fly-half Morath capitalised on an early chance to open his account for the club on his starting debut when converting a straight 30m penalty after 10 minutes during which Knights had enjoyed the better of the exchanges.
It took Hartpury 16 minutes to breach the Doncaster 22 but they opened their account two minutes later when scrum-half Richard Bolt spotted a gap five metres out and reached out to score near enough for half-back partner Luke Cozens to convert.
Cozens extended their lead with a 20thÂ minute drop goal after Bolt had helped turn defence into attack from inside his own half.
Knights suffered another blow three minutes later when influential skipper Michael Hills had to be helped off with a knee injury - Josh Tyrell coming on for his first game of the season following a knee operation.
Knights lost their earlier sparkle and were finding the visitors hard to break down.
Morath made amends for missing an earlier kick when cutting the deficit to four points with a second penalty success on 38 minutes.
Knights were penalised from the restart and they came under a spell of sustained pressure from the resulting free-kick which eventually led to hooker Luke Stratford forcing his way over from close range for a second converted try.
Cozens had the chance to extend Harpury's 17-6 lead but was wide with an angled injury-time penalty.
Knights knew they needed to score first after the break and their hopes received a boost on 46 minutes when Hartpury flanker Rob Langley was sin-binned for ten minutes during which time they scored two tries.
The first came from a penalty try when Hartpury were adjudged to have collapsed the scrum.
The second came when Morath fed Lewis down the left in the Hartpury 22 and he in turn found full-back Cameron Cowell on his inside close to the line.
Morath made it 23-17 with 66thÂ minute penalty prior to Hartpury going close during their first sustained attack of the half.
Wing Steve McColl effectively put the result beyond doubt when intercepting a pass inside his own half and leaving the cover for dead.
Hartpury finished strongly but Knights dug deep to deny them a losing bonus point.
Knights: Cowell, McColl, Hayes, Matavasi, Lewis, Morath, James; Hislop, Hunter, Quigley, Eames, Hicks, Calladine, Hills, Ryan. Rep: Tyrell, Williams, Sprotson, Challinor, Malcolm, Seniloli, Foley.