When the engines were eventually shut off late on Sunday afternoon, it was Frost who emerged as the new series leader, courtesy of two hard-fought runner-up finishes, with the day's double race winner, Saiger, rocketing up the standings from third equal to second.
Rees slipped from first to third, albeit just eight points behind Frost and five behind Saiger, with anything still possible at the final round.
Perhaps the stand-out rider on Sunday was young Suzuki ace Mettam.
The 20-year-old, appearing at only his second event on the powerful superbike, showed he was a quick learner as he finished a close third in the first F1 race and then led the second race for several laps, following a daring pass that saw his shoot past both Saiger and Frost in the same corner, before eventually being overtaken and forced to again settle for third.
This performance elevated Mettam from eighth to fifth in the F1 class standings.
With the margins between success and failure so tight, Suzuki's Frost knows he has his work cut out to retain the Suzuki Series crown and also hope that he can prevent Honda's Rees bouncing back and making it three winning seasons in a row on the streets of Whanganui.
The 49-year-old Rees has won at Whanganui six times now since his first victory there in 1990, but Suzuki has dominated the Suzuki Series wins overall, their riders winning the main trophy on all but two occasions since the series was created in 2008.
Joining the fray at Manfeild was visiting Northern Irish rider Michael Dunlop, the 2016 Isle of Man champion.
Racing a GSX-R1000 supplied by Suzuki New Zealand, Dunlop "had a bit of a play"during practice day on the Saturday at Taupo but was unable to get official clearance from his insurers to race on Sunday, but he made up for that by racing at Manfeild.
He withdrew from the first F1 race with mechanical problems and finished sixth in race two, and, despite his bad luck thus far, he still remains one of the favourites to win on the streets at Whanganui on Boxing Day.
The third and final round of the series is set for the public streets of Whanganui, on the world-famous Cemetery Circuit, on Boxing Day, and it could not be much tighter at the top of the premier class and a white-knuckle spectacle is promised for the thousands of race fans who will no doubt again abandon their Christmas dinners in favour of a few high-octane thrills and spills.
Other class leaders after racing on Sunday are Whakatane's Damon Rees (F2/600 supersport); Taumarunui's Leigh Tidman (F3/sport bikes); Tauranga's Duncan Hart (super motard); Tauranga's Colin MacGregor (Bears, non-Japanese bikes, seniors); Bulls' Ashton Hughes (Bears, non-Japanese bikes, juniors); Pukerua Bay's Glen Skachill (Post Classic, Pre-89, senior); Auckland's Scott Findlay (Post Classic, Pre-89, junior); UK's John Holden and Tauranga's Robbie Shorter equal first with and Te Puke's Barry Smith and Tauranga's Tracey Bryan.