Leinster A 28 Doncaster Knights 37: Rally proves enough to clinch last eight Cup spot for Knights

Clive Griffiths’ side were 21-8 down early in the second period against a side who had won all five previous pool games scoring a bonus point in each.

However, on the back of some fine defensive efforts, they took control after Leinster saw two players sin-binned within seconds of each other around the 50th minute.

Lock Ian Hagle was yellow-carded for a professional foul as Matt Challinor edged near between the posts and then, as Doncaster sought to exploit the extra space, Leinster full-back Barry Daly slapped down a long pass that would have provided a certain score for Tyson Lewis.

Referee Mike English not only brandished another card but also awarded a penalty try.

Initially, Knights struggled to make the most of playing against 13 men but, just before Nagles’ return, full-back Paul Jarvis produced a stunning 80m solo try, beating a raft of defenders, to get them back to 21-20.

Then, with Leinster returned to a full complement, they reclaimed the lead - and a try bonus point - after winger Junior Bulumakau finished off replacement forward Adam Batt’s break down the right touchline.

Doncaster - with Samoa blindside Josh Tyrell enjoying a super debut - knew two points, in all likelihood, would see them qualify as one of three best pool runners-up, but they made sure of qualification by pushing on to secure this impressive win.

Simon Humberstone slotted his second penalty and, after Knights charged down a kick, Mat Clark set up position for the excellent Matt Challinor to get over for their fifth try, Declan Cusack improving.

Two-time Cup winners Leinster - so impressive in this competition - rumbled over via Sean McNulty’s driving maul deep into injury-time, Charlie Rock converting, but it was Doncaster who came away worthy victors.

It was the perfect response, too, after throwing away victory against Bristol a week earlier and they will now wait to see who is up next in the last eight.

Knights had started in good nick with a well-worked set-piece try from Joe Sproston, the tighthead prop who benefitted from a short-side line-out move.

Nevertheless, Leinster quickly found their rhythm with three tries in just 15 minutes, illustrating their slick football at times along the way.

Winger Jack Kelly had already threatened with an early 50m break and, after Sproston’s score, the hosts got up and running as centre Gavin Millun picked a lovely line to glive through from 22m out.

Ciaran Frawley slotted the first of his three conversions and, though Humberstone slotted a penalty soon after for Doncaster, his side were quickly unpicked again.

This time, rather alarmingly, full-back Jarvis was left rooted to the spot as Leinster loosehead prop Ed Byrne sidestepped past him and sprinted over from 20m, winger Lewis already left bemused, too, earlier in the play.

Frawley improved and did so again when Nick McCarthy sniped through from behind a ruck in the 24th minute although, that time, English did seem to inadvertently act as a foil for the Leinster scrum-half.

But to their credit, spirited Knights did not crumble and, with the irrepressible Tyrell putting himself about, Jarvis also making one break and Humberstone causing problems with a midfield chip, they asked questions of the Leinster defence.

Although they could not narrow the deficit at that point, at 21-8 the knew a positive start to the second period could see them make ground.

Aided at first by that double sin-binning, they certainly did that.

Leinster A: Daly; Kelly, Mullin (O’Brien 68), Reid, O’Brien; Frawley (H Byrne 72), McCarthy (Rock 65); E Byrne (Heffernan 80), Kelleher (McNulty 9 BB reversed 12, McNulty 65), Bent (Aungier 71), Mick Kearney, Nagle, Murphy, Max Kearney (Dowling 50), Timmins.

Doncaster Knights: Jarvis; J Bulumakau, Klim, Clark, Lewis; Humberstone (Cusack 73), Heaney (James 65); List Hunter (Langdon 33 BB rev 40 Langdon 62) Sproston (Williams 65), Challinor, Hicks, Tyrell (Hill 62), Owen, Shaw (Batt 65).

Referee: Mike English (WRU)