They led 12-2 early in the second period against Catalans Dragons and, having been pegged back to 12-12, pressed ahead with Craig Hall’s 80m intercept try.
However, he could not convert and that proved crucial as the French side responded with Lewis Tierney’s 76th minute effort, Sam Tomkins holding his nerve to give the Challenge Cup holders their first away win in six months.
For the Robins, who lost props Mose Masoe and Mitch Garbutt to head injuries late on and gave 20-year-old Adam Rooks a debut, it was too reminiscent of when they squandered a 14-point lead to lose 24-22 against Salford Red Devils last month.
“When you see us lead, get run down again on the death and lose by two it reminds us of Salford,” conceded Sheens, who revealed Australian Kane Linnett also partially tore a pectoral muscle that could see him miss Friday’s trip to Huddersfield Giants.
“We weren’t as dominant as we were against Salford. We were a much stronger side that day.
“This time we really struggled for numbers. We didn’t have enough big men and then we lost Mose (Masoe) and (Mitch) Garbutt in the last 10 minutes it hurt us.
“We lost the ruck partly because of that; we were carrying a couple of busted guys so we ran out of numbers and steam.
“We were just hanging on. The tries were the same; it was just a couple of kicks and the last one from the sidelines by Tomkins was the one that buried us. Otherwise we might have survived.”
It was KR’s own Tomkins – Joel – who thought he was going to have the upper hand.
Back from a two-game ban for questioning the integrity of a match official, he scored a brilliant solo try, rounding his younger sibling in the 49th minute.
But Samisoni Langi, the Tongan centre who had a superb second period, dabbed in a grubber kick that saw Tierney sneak in and beat a flat-footed Will Oakes to the bouncing ball.
It was not an easy conversion attempt for full-back Tomkins – especially in front of the East Stand that had barracked him all afternoon – but he succeeded.
It was just what they needed after an embarrassing 46-0 home loss to Salford Red Devils the week before but the Robins, despite missing injured hooker Tommy Lee, will know they should have seen this one out.
With a dire first half finishing level at 2-2, they seemed to have taken control with two tries early in the second period.
First, after Josh Drinkwater’s kick forced a drop-out, Chris Atkin’s delayed pass out of acting-half sent Weller Hauraki over untouched from close range for a converted try.
Then Tomkins did his stuff. Atkin, who made a difference coming on at nine, was again the instigator giving the ex-England second-row room to move down the blindside from 40m out.
Tomkins did brilliantly to fend off a defender while holding the ball outstretched one-handed before fooling his brother turning him inside out to reach the line.
Yet Catalans, who had lost forwards Remi Casty, Sam Moa and Greg Bird to first-half head knocks, remained undeterred as they levelled the game with back-to-back tries on the hour.
Brayden Wiliame was too strong for Jimmy Keinhorst and, though Tomkins missed the conversion attempt, his side were in immediately after.
Langi surged clear down the opposite flank on the right and Lucas Albert supported for Tomkins to make it 12-12. That classy intercept from Hall, who swapped first half penalties with Tomkins, relieved the pressure but then there was that final twist.
Catalans head coach Steve McNamara, who was born in Hull and captained the club across the city, said: “Sam’s a big-game player. He’s done it twice for us now; once against Warrington and then again now in what was a very tricky wind.
“We were completely embarrassed by what happened last week and knew we had to find some sort of response. We did but we had to fight really hard.”
Hull KR: Dagger; Hall, Keinhorst, Vaivai, Oakes; McGuire, Drinkwater; Masoe, Addy, Lawler, Linnett, J Tomkins, Hauraki. Substitutes: Garbutt, Atkin, Rooks, Shaw.
Catalans Dragons: S Tomkins; Yaha, Langi, Wiliame, Tierney; Gigot, Smith; Casty, Albert, Moa, Edwards, Whitley, Bird. Substitutes: Bousquet, Baitieri, Jullien, Goudemand.
Referee: James Child (Dewsbury).