Worcester offered precious little as they crashed to their sixth defeat in their last seven Premiership encounters, but Simon Whatling’s last-minute penalty secured them a barely-deserved bonus point.
It was Leeds’ third straight home success in the Premiership, their sixth victory from their last eight home matches in all competitions and takes them to within two points of their relegation rivals.
However, with four of their remaining six games away from home – they now face daunting trips to Leicester and Wasps – the Tykes’ survival prospects remain very much in the balance.
A win was imperative for Leeds after last week’s agonising defeat at Sale, the Tykes eventually going down 35-24 after leading 24-16 going into the last two minutes of normal time.
They attacked Worcester from the first whistle and their vibrant approach reaped dividends after four minutes when Bell forced his way over the line from close range following good work by Justin Marshall.
De Marigny failed to convert the touchdown and then missed a penalty six minutes later as the Tykes initially struggled to convert their dominance into points.
Leeds extended their lead midway through the opening period, however, as de Marigny came good at the third time of asking to convert a penalty and edge his side 8-0 ahead.
Four minutes later Shane Drahm notched a penalty to get Worcester off the mark but the Tykes responded in the perfect manner and produced a try of breathtaking quality.
The impressive Tom Biggs was the catalyst as he embarked on a rampaging run from inside his own half before finding Jon Dunbar.
Dunbar found Bell to his left and he kept the move flowing with another neat offload to Rayno Gerber.
Worcester struggled to cope with Leeds’ bewildering array of inter-passing and when Gerber’s pass found de Marigny in space in the left-hand corner, the Italian scampered over the line to put the seal on an exhilarating move.
De Marigny again added the extras as Leeds established a 15-3 lead beforeDrahm missed a penalty on the half hour mark.
The Worcester fly-half reduced Leeds’ advantage to nine points with his second penalty of the half, before de Marigny missed another penalty shortly before the interval.
And Leeds’ nerves set in when Drahm registered a drop goal after 56 minutes to haul his side right back in contention at 15-9.
But de Marigny soon converted another penalty to make it 18-9 before Drahm replied with one of his own to complete a personal 12-point haul.
Worcester replacement Siaosi Viali was sinbinned in the closing stages before de Marigny added a late penalty to complete a miserable night for the visitors in front of a crowd of just 3,718 – the Tykes’ lowest Premiership attendance of the season.
However, Worcester had the final word as Whatling grabbed a last-minute penalty to secure his side a bonus point.