Japan's premier single-seater series' traditional Suzuka rookie test in December often provides a reliable indicator of who is going where next year - fuelling plenty of 'hot stove league' speculation.

The term 'hot stove league' is used in Japan in the sense that the 'silly season' is used in Europe, and finds its roots in baseball terminology - referring to fans of the sport huddling around a 'hot stove' to discuss the latest transfer rumours in the off-season.

And it's not just teams further down the order that are set for change - even some of Super Formula's top squads are looking likely to sport new line-ups in 2019.

Toyota powerhouse TOM’S is one such team, as 2018 runner-up Nick Cassidy tested for the squad at Suzuka.

The Kiwi racer and TOM’S have a relationship dating back to 2015, and the two parties have together won championships in both Japanese F3 and Super GT, which makes the move logical.

He would replace James Rossiter, whose relationship with Toyota looks on the wane in the wake of his participation in a Nissan Super GT shootout alongside Dani Juncadella and Frederic Makowiecki.

Meanwhile, Cassidy’s place at Kondo is likely to be taken over by 2016 champion Yuji Kunimoto, who at Suzuka was forced to move over from Inging to make way for rising star Sho Tsuboi.

Tsuboi, 23, annihilated the field in this year’s All-Japan F3 championship with 17 wins in 19 races, and Toyota is set to reward him with a seat in a team that has won two out of the last three Super Formula titles, alongside Hiroaki Ishiura.

Elsewhere, KCMG has been rumoured to expand to two cars next year, although it remains unclear who would partner incumbent Kamui Kobayashi in such a scenario.

Artem Markelov is believed likely to race in Super Formula next year with a Toyota-powered team, but a deal for the Russian to test for Team LeMans fell apart at the last minute.

Markelov was therefore absent from the Suzuka test entirely, but should the second KCMG car come to fruition (the team only tested Kobayashi), the Formula 2 star would be a candidate to fill that seat.

Conversely, there is a possibility that Team LeMans - one of Super Formula’s more successful teams but one that has entered a period of decline recently - could scale back to just one car for Kazuya Oshima.

The team did test several other drivers in Suzuka, but of those, only European F3 race winner Ralf Aron is believed to be a viable candidate for a possible second car, although Markelov could also yet strike a deal.

Naoki Yamamoto, Dandelion Racing Photo by: Masahide Kamio

Motorsport.com reported last month that Honda is set to overhaul its Super Formula line-up for 2019, and this month’s Suzuka test offered a glimpse into how that will shake out.

Reigning champion Naoki Yamamoto now seems destined to join Dandelion Racing in a direct swap with Tomoki Nojiri, who will partner the recently-confirmed Dan Ticktum at Mugen.

Nirei Fukuzumi will join Yamamoto in moving across from Mugen to race at Dandelion, as Nobuharu Matsushita returns to F2 in Europe to pursue his F1 dreams.

Ex-DTM driver Lucas Auer’s place in B-Max/Motopark was also recently announced by Red Bull, but the identity of his teammate remains a question mark.

Harrison Newey, son of Red Bull F1 design guru Adrian, is considered the favourite after testing for the squad at Suzuka, but Haas F1 test driver Pietro Fittipaldi is also thought to be a contender for the seat.

Nakajima Racing could field an all-new line-up in 2019, with Narain Karthikeyan expected to switch to Super GT and Takuya Izawa deemed unlikely to stay with the team.

F2 race winner Tadasuke Makino is all-but-certain for one of the Nakajima drives, with F3 racer Alex Palou, Bertrand Baguette and Fittipaldi all in the mix for the other seat.

Baguette has been racing with Nakajima in Super GT since 2014 and was eyeing a move to Super Formula, but was absent from the Suzuka test.

Elsewhere, single-car Honda outfit Real Racing may pull the curtains down on its Super Formula team next year and instead focus its efforts on its fledgling Super GT outfit.

2019 Super Formula - expected line-up and rumoured drivers:

Team Drivers Dandelion Naoki Yamamoto Nirei Fukuzumi Mugen Tomoki Nojiri Dan Ticktum Nakajima Tadasuke Makino Alex Palou Pietro Fittipaldi Bertrand Baguette B-Max with Motopark Lucas Auer Harrison Newey Inging Hiroaki Ishiura Sho Tsuboi Kondo Kenta Yamashita Yuji Kunimoto Impul Yuhi Sekiguchi Ryo Hirakawa KCMG* Kamui Kobayashi Artem Markelov LeMans** Kazuya Oshima Ralf Aron Artem Markelov TOM’S Nick Cassidy Kazuki Nakajima Real*** -

Key

Bold - Confirmed

Regular - Expected but not confirmed

Italics - Rumoured

* May expand to two cars

** May scale down to one car

*** May not compete next year