Ryan Brierley opened the scoring on five minutes with tries from Sam Barlow and Greg McNally handing the Centurions a 16-0 advantage after 20 minutes.
Brierley added a second try with 15 minutes left of the first half, before Kay notched his first of the day three minutes later to all-but end Doncaster’s chances of a repeat of their 24-16 success last season.
Mike Emmett‘s converted try briefly halted the Leigh attack, however they were soon back on the scoresheet after the interval with Kay grabbing his second try of the day three minutes after the break.
Emmett responded eight minutes later for Doncaster with his second of the game but Leigh clicked through the gears thereafter.
Kay sealed his hat-trick on 54 minutes before adding a fourth as the hour mark approached and Martyn Ridyard crossed with 17 minutes to go.
Sam Doherty gave the home fans something to cheer late on but Tom Armstrong made sure the visitors had the last say with a 73rd minute try.
The Hawks would have been buoyed by their 18-6 success against Dewsbury last week but they were never in touch against the imperious Bulls at Odsal.
In front of a 5,019 crowd, Adam O’Brien added the Bulls’ third and the hosts were out of sight when Ryan Shaw crossed to make it 22-0 after just 19 minutes.
The Hawks, who had Brett Delaney, on dual registration from Leeds Rhinos, in their side, stopped the onslaught for a brief period but Shaw was in again on 31 minutes before Danny Williams went in on the stroke of half time.
Shaw was successful with all but one of his kicks, giving the home side a commanding 34-0 lead at the break.
Tom Olbison was next to go over, helping the Bulls hit the 40-point mark on the hour.
Hunslet were given a brief reprieve when Luke Briscoe went over on 63 minutes, but Shaw completed his hat-trick three minutes later.
O’Brien and Mullaney added further scores before Shaw closed out the scoring, kicking the final goal of the game with minutes to go to complete a fine 28-point personal haul.
Staying in West Yorkshire, Featherstone bounced back from their 40-4 drubbing by Bradford last weekend with an impressive 24-12 win over Halifax at The Shay.
Paul Sykes and Tom Johnstone scored first-half tries for Rovers with Steve Tyrer responding for the hosts to make it 10-6 at the break.
Andy Ellis helped his side to a 16-6 lead on the hour before Mitch Calahane threatened to bring Fax back into the tie. But Joe Arundel, playing on dual registration from Wakefield, secured the win when he crossed on 78 minutes.
In the closest game of the weekend, Dewsbury Rams edged out Whitehaven 23-16 at the Tetley’s Stadium.
Anthony Thackeray scored a trademark ‘show and go’ try to give the Rams the lead for the first time on the half hour mark and he notched a drop goal soon after.
But, Declan Hulme brought his side to within three points on the stroke of half time and the visitors re-took the lead through Jessie-Joe Parker on 49 minutes.
Craig Calvert‘s try with just over ten minutes to go made sure of a tense finish but the Rams held on.
Jarrad Stack and Perry Whiteley brought Town to within two points shortly after half time but Jon Wallace and Tom Gilmore scored before the hour to take London clear.
Batley kept within touching distance of their hosts thanks to tries from Wayne Reittie, Alistair Leek and Sam Scott, plus two goals from Scott Leatherbarrow, but the day was all about Patch Walker who moved to within two points of 1,000 in his career.