The four invaluable points earned have not removed them from the bottom of the league table, but this victory has left Doncaster just one point behind fellow relegation candidates Jersey.
If the side coached by Clive Griffiths were able to reproduce the flair, enterprise and support play seen in the opening 40 minutes, during which a complacent Leeds were flattened, Doncaster may well survive.
With six games remaining against Moseley, Rotherham, Bedford, Nottingham, Jersey and Plymouth, three of which are at Castle Park, this win has provided self-belief just when it is required in the most challenging of circumstances.
On this evidence alone, Rotherham would be foolish to assume they can repeat last season’s win at Castle Park next month for, as Leeds quickly discovered, if Griffiths’s team use their possession intelligently and attack at pace, opponents suffer.
Leeds left South Yorkshire with a losing bonus point but they must transform their outlook if they are to achieve a top-four place enabling them to compete in the promotion play-offs.
The Headingley side also have six league games left – Cornish Pirates, London Scottish, Moseley, Rotherham, Bedford and Nottingham, with three at home – in which to guarantee the season’s aim.
Considering Doncaster’s previous record of only two wins in 15 Championship contests and their frequent handling errors in recent games, no-one could quite believe the skill, speed and force which shocked and dismantled Leeds during the first half.
Inspired by an outstanding performance by Tongan flanker Will Hafu, Doncaster attacked from the start and scored a super try after only three minutes.
The move, began by Hafu and supported by prop Tom Davies, stretched the Leeds defence. Flanker Adam Kettle then instantly demonstrated quick thinking by passing to winger Michael Keating who dashed in to score a thrilling try.
Doncaster’s forwards controlled possession and territory to deprive Leeds, who, apart from No 8 Ryan Burrows, failed to make any impact.
Fly-half Rory Clegg kicked the ball aimlessly and collectively Leeds were prevented from leaving their own half and, therefore, could not threaten Doncaster’s line.
In contrast, Doncaster’s fly-half, Jamie Lennard, excelled and contributed significantly to his team’s success.
Penalties on nine, 22 and 30 minutes followed by his converted try on 37 minutes – his second conversion – enabled him to finish with 18 points, a match-winning effort that provided Doncaster with a surprising half-time lead of 23-3.
Leeds, embarrassed earlier, to their credit recovered professionally during the second half which they controlled to the extent that Doncaster came close to defeat and failed to score again.
The Leeds pack won most of the ball, ensuring the game was then played almost entirely in Doncaster’s half. A counter-attack and weak tackling let in winger David Doherty to score his 11th Championship try on 53 minutes and once the Leeds forwards, now dominant, were awarded a penalty try in the 76th minute, again converted by Clegg, only six points separated the sides.
The momentum was clearly favouring Leeds and the question was whether Doncaster had sufficient reserves of energy to defend a lead of 23-17.
Stoppages meant a stoppage time of 12 minutes, so Leeds still had the opportunity to manufacture a lethal breakthrough.
Doncaster’s character, combined with strong and swift tackling, stopped any more dangerous advances, allowing them to cling, somewhat precariously, to their lead and complete a priceless win.
“I’m relieved and delighted,” said Griffiths. “This massive win shows what we can do. We defended for our lives and it makes a difference when you hold on to your passes.
“The boys got their reward, but we still have to learn how to kill games and we know we are in a hole.
“We’re only one point behind now, but the boys know the challenge they face.”
As Doncaster celebrated, Leeds coach Diccon Edwards reflected: “You’ve got to get your intensity, attitude and work-rate right, and if you don’t, you won’t win any game.
“We didn’t have that for 40 minutes. If we’ve learnt anything from this match, it is the understanding that attitude is absolutely paramount if you are going to be successful.”
Doncaster Knights: Braid, Keating, Simpson (Mama 22), Luke, Lewis, Lennard, Bedford, Davies (McGovern 67), Buckley (Bergmanas 70), Cronin, Challinor, Parsons (Smith 76), Kettle, Hafu, Planchant.
Leeds Carnegie: McColl, Georgiou (Lucock 64), Goss, Burden, Doherty, Clegg, Hampson (Frost 70), Clegg, Harris (Imiolek 60), Nilsen (Graham 67), Tussac (Currie 56), Green (Smith 56), Myerscough, Baldwin, Rowan, Burrows.
Referee: R Campbell.