London Welsh celebrated the New Year in style by guaranteeing their place in the Championship play-offs with victory over Doncaster Knights, but only by the width of the crossbar.

In an extraordinary finish with, Welsh leading 21-19, Doncaster full back Stephen McColl’s penalty from five metres inside his own half cannoned back off the crossbar, allowing the Dragons to escape Castle Park with the points.

Welsh had earlier opened up a 15-3 lead thanks to tries from Josh Drauniniu and Paul Mackey, but Andy Wright’s try and the boot of Tristan Roberts saw Doncaster edge ahead in the second half.

The lead would change hands three more times, with the decisive strike coming from Welsh fly half Jamie Lennard on his return to his former club.

When Roberts’ penalty curled wide Doncaster’s chance seemed to have gone until McColl stepped up with the penultimate kick of the game only for the crossbar to come to Welsh’s salvation.

Welsh were given a dream start when Josh Drauniniu crossed for his 13th Championship try of the season in the second minute.

The ball breaking kindly for Errie Clasassens and he released Drauniniu to race clear from half-way. Lennard added an excellent conversion.

Doncaster responded well, though, pinning Welsh in their own 22 and a good cover tackle by Paul Mackey forced the lively Matt Williams into touch.

But the home side’s pressure was rewarded in the 10th minute when Roberts bisected the uprights after Matt Challinor and James Craig combined and Roberts took the three points on offer with advantage being played to the Knights.

Lennard used his local knowledge to good effect to take play into the Doncaster 22 and with Welsh awarded a free kick for numbers at the ensuing lineout, Dom Shabbo was denied in the corner by some good defence.

The reprieve was short lived, though, as play was brought back for Doncaster not being ten metres and Welsh opted for the scrum. This time when the Dragons spread play Shabbo picked up well and Mackey dummied nicely before crossing for his first try since his comeback from injury.

Lennard couldn’t add the extras but Welsh were taking their chances. Two visits to the Knights 22 and two tries.

The home side threatened when Drauniniu knocked on a high ball and Petaia Gidlow drove into the Welsh 22, only for referee Paul Knowles to spot a slight knock on when the centre went to ground.

Welsh extended their lead ten minutes before the break when Lennard converted a penalty from five metres inside the Doncaster half, after the Knights were penalised for a pull back off the ball.

Doncaster had enjoyed more of the possession but it was Welsh that possessed the more clinical edge, but just when the home side seemed to be running out of ideas they struck through Wright.

Roberts’ clearance only found Claassens, but his up and under was picked off by Nathan Jones and his offload inside released Wright to outpace the cover defence and slide over next to the posts.

Roberts converted and then added a penalty with the last kick of the half from in front of the posts to reduce Welsh’s early lead to just two points, as the sides headed to the warmth of their dressing rooms on a bitterly cold Doncaster day.

Williams very nearly intercepted Lennard’s floated pass but Doncaster were ahead when Roberts converted his third penalty after Epi Taione was penalised for holding on in the tackle after picking up from the back of a scrum.

Crucially, for the second time Roberts then failed to find touch with a penalty. That was compounded by hooker Steve Boden being penalised for dummying his lineout throw and McColl badly slicing his kick to rather kill Doncaster’s early second half momentum.

Lennard nudged Welsh back in front with a hanging kick that just had the legs from half-way, after Claassens’ half break saw Doncaster penalised for not rolling away.

A forward pass gifted the Knights good field position on the Welsh 22 and although Doncaster could find no way through the Dragons defence Roberts dropped back into the pocket before landing his second drop goal of the game.

Immediately, though, all of Doncaster’s good work was undone by hands in the ruck and Lennard stroked Welsh back in front with his third penalty.

When the Welsh scrum went down with five minutes to go, Roberts stepped up only to see his attempt curl just wide – his first miss in six attempts.

Doncaster were the ones asking the questions, but the Welsh defence was able to come up with the answers.

That was until added time when Welsh conceded a penalty five metres inside their own half and McColl stepped up, only to see his strike cannon back off the crossbar and cue one almighty scramble, during which Doncaster were penalised for going over the top in their eagerness to get the ball back.

Lennard thumped the ball into the stands and Welsh had the win.

Doncaster Knights scorers: Tries: Wright; Cons: Roberts; Pens: Roberts (2); Drop Goals: Roberts (2).

London Welsh scorers: Tries: Drauniniu, Mackey; Cons: Lennard; Pens: Lennard (3).

Doncaster Knights: Stephen McColl, Andy Wright, Chis Briers, Petaia Gidlow, Matt Williams, Tristan Roberts, Nathan Jones, Dan Frazier, Steve Boden, Michael Cusack, Matthew Challinor, James Craig, Latu Maakafi, Neil Cochrane ©.

Replacements: Stuart Corsar for Frazier (56min), Lewis Thiede for Cusack (65min), Chris Hallam for Farivarz (67min), Jacob Rowan for Jones (67min), Dominic Parsons for Craig (74min) Replacements not used: Thomas Doughty, Dougie Flockhart.

London Welsh: Errie Claassens, Paul Sampson, Dominic Shabbo, Paul Mackey, Josh Drauniniu, Jamie Lennard, Shawn Pittman, Vili Ma’asi, Lorne Ward, Mike Powell, Mrtin Purdy, Jon Mills ©, Michael Hills, Ep Taione, Replacements: Matt Corker for Mike Powell (h-t), Waisea Luveniyali for Sampson (62min), Will Johnson for Ward (67min), Ben Russell for Purdy (69min), Rob Lewis for Runciman (71min).

Replacement not used:Robert Herrin, James Lewis.