Academy product Broadbent, 20, was drafted in for only his fourth appearance after head coach Richard Agar saw FIVE of his first-choice backline absent for the Super League kick-off against Wakefield Trinity.
Leeds had been 16-4 down in the first period with Wakefield winger Tom Johnstone scoring a stunning solo effort.
They recovered to go in 22-16 ahead only to see Johnstone pluck Luke Gale’s kick out of the sky and race 80m to level matters in the 45th minute.
Still, Batley-born Broadbent was on hand to race onto a brilliant short pass from Richie Myler, the full-back who excelled here carrying on his stellar 2020 form, and give his side a lead they would never lose in the 59th minute.
Gale, who won his race to be fit in time for kick-off after a torn pectoral, slotted a penalty in the 75th minute to leave Leeds 28-22 ahead only for a late worry when Liam Sutcliffe fumbled the restart.
However, just as Wakefield aimed left to try and get Johnstone in for his hat-trick, Broadbent popped up once more for a crucial intercept.
Trinity - who were technically ‘hosts’ at Emerald Headingley - will rue a missed chance when, at 22-22, Bill Tupou did get on the outside of Broadbent to race 50m clear.
He had support but as he went to pass, Myler gambled and got his hand in the way to break down the play, Tupou realising he could have dummied past the Lance Todd Trophy winner.
Tupou also failed to take a pass after Johnstone, in brilliant form on Trinity’s left, made a trademark break but it is hard to say Leeds did not deserve the spoils in an absorbing contest which was high quality given it was the opening game of the season.
Leeds led 22-16 after a thoroughly entertaining first period.
They had gone 4-0 ahead when Gale’s chip saw Alex Walker forced back behind his own goalline and, in the next set, Myler’s cut-out pass sent Luke Briscoe in.
The impressive Kruise Leeming struck an excellent 40/20 kick as Rhinos started with confidence.
Nevertheless, Trinity managed a try out of nothing as Johnstone scored that stunning 80m solo effort on nine minutes.
The England winger bravely decided to take Tom Briscoe on on the outside deep inside his own half and was proved correct, his experienced opponent looking surprised as the Wakefield man eased into space.
But Johnstone still had work to do, opting to dummy inside to his support before beating Myler for pace, too.
At the start of a World Cup year, it was a perfect audition.
For all Rhinos were missing so many players, it did not show as they continued to press hard encouraged by Leeming’s promptings at dummy-half.
However, once more they were undone when Trinity scored with only their second real attack in the 15th minute.
Mason Lino, their half-back signing from the NRL, put Kelepi Tanginoa through a gap initially and then, onthe last play, linked wonderfully with Reece Lyne for Innes Senior to cross.
Lino slotted the first of his three goals, his second coming after the ex-Newcastle Knights player showed a nice touch before Jacob Miller dummied his way through on a fine run to send Matty Ashurst over inthe 20th minute.
At 16-4, Leeds could have easily fallen apart but, instead, they responded with a stunning spell of their own - three tries in 13 minutes.
The first came after Broadbent made a surging run infield to set up position for Myler, once more, to execute for Luke Briscoe.
The winger could not get to the line, this time, but Alex Sutcliffe - the other youngster making up Rhinos’ makeshift centre paring - was on hand.
Brad Dwyer dummied through some weak Trinity goalline defence and then, after Matt Prior stole possession off Chris Green, Gale bounced off a tackle before perfectly ushering a straightening Myler through a gap to score.
Rhyse Martin’s third conversion gave the ‘visitors’ the interval lead and they came home strongest but Trinity will be encouraged with their efforts.
Wakefield Trinity: Walker; Senior, Lyne, Tupou, Johnstone; Miller, Lino; Fifita, Crowther, Arona, Ashurst, Tanginoa, Westerman. Substitutes: J Wood, Batchelor, Green, Tangata.
Leeds Rhinos: Myler; T Briscoe, J Broadbent, A Sutcliffe, L Briscoe; L Sutcliffe, Gale; Oledzki, Leeming, Prior, Mellor, Martin, Tetevano. Substitutes: Dwyer, Thompson, Donaldson, Smith.
Referee: Scott Mikalauskas (Leigh)
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