Following a number of big-name moves and shock announcements, this season has produced one of the most unpredictable and baffling Formula 1 driver markets in recent memory.

It looked set to be a quiet summer of few changes heading into 2019 after Mercedes announced new deals for reigning world champion Lewis Hamilton and Valtteri Bottas ahead of the German Grand Prix in July.

The decision to retain its driver line-up appeared to leave Daniel Ricciardo - the last remaining big-name driver without firm plans for next year – with the sole option of extending his tenure at Red Bull. But in a move that took everybody in the paddock by surprise, Ricciardo set off a chain reaction of unexpected switches with his bombshell decision to leave Red Bull for Renault in 2019.

Ferrari became the latest team to reveal its plans for 2019 ahead of this weekend’s Singapore Grand Prix with the news it will promote its protégé Charles Leclerc to replace Kimi Raikkonen, who will return to the Sauber squad that launched his F1 career in 2001.

Who will make the next move?

As the driver merry-go-round continues, there are still nine seats to be confirmed. Haas looks best-placed to be the next team to reveal its line-up with seats now locked out at Mercedes, Ferrari, Red Bull and Renault.

Team principal Guenther Steiner said he expects a double announcement to come in the next “two weeks”, with Kevin Magnussen likely to stay on for a third season, while Romain Grosjean has strengthened his position thanks to a string of improved results in recent races.

Sergio Perez revealed he had already signed a deal for 2019 back at Spa, and with a potential return to McLaren now off the table given Lando Norris’ promotion alongside Carlos Sainz – who in turn replaced the exiting Fernando Alonso – the Mexican looks odds-on to remain at Force India.

He is set to be joined at the Silverstone-based outfit by Williams driver Lance Stroll, who is expected to follow his father Lawrence Stroll to the team after the Canadian businessman led a consortium to rescue Force India from administration.

It seems to be a question of when - rather than if - that deal is completed. A switch could happen as soon as the Russian Grand Prix at the end of the month but Force India is understood to be uneasy about mid-season changes as it looks to recover lost ground in the constructors’ championship. Team principal Otmar Szafnauer said on Friday in Singapore he considered a switch this year to be “unlikely”.

Either way, Stroll is almost certain to be racing in Force India colours come the 2019 curtain-raiser in Melbourne next March.

Ocon’s options looking bleak

The Force India situation means Esteban Ocon is set to lose out on his drive and could be off the grid altogether in 2019. With a lack of available seats remaining on the grid, Ocon’s links to Mercedes have ultimately worked against him, persuading the likes of McLaren and Toro Rosso against making a move for the highly-rated Frenchman.

Ocon had a deal agreed in principle with Renault for next year until Ricciardo inadvertently blocked his path. Failure to tie-up a deal has left Mercedes boss Toto Wolff highly frustrated, while Ocon admitted his chances appear slim for landing a seat for next season.

“There are still hopes, but less and less,” Ocon conceded. “That's a bit why I'm disappointed at the moment, to see that it's not only results that come in play, it has to be other things. That's why I'm disappointed to be in that situation. It's hard to believe that I was in a great position two months ago and things have gone that way now.”

One of those options could be Williams, where there is at least one seat to be filled following Stroll's impeding departure - which could provide Ocon with a saving grace. Sergey Sirotkin signed a multi-year deal with the Grove-based squad at the start of the season and while there has been no suggestion his position could be under threat, Mercedes could test its resolve in a bid to get both its starlets onto the grid.

Adding to Ocon's precarious situation is the additional dilemma of where to place junior George Russell should he go on to win the Formula 2 Championship he currently leads from Norris. Pulling off back-to-back titles in a similar fashion to Leclerc before him would leave Mercedes angling to find a seat for the Briton, given drivers cannot continue in F2 after becoming champion. Mercedes might use its engine supply deal with Williams as a sweetener in an attempt to crowbar both Ocon and Russell into the team.

Another dimension into the complex Williams situation comes in the shape of reserve driver Robert Kubica, who would be contractually obliged to replace Stroll should he move to Force India before the end of the current campaign. That would provide Williams with a chance to evaluate the Pole against Sirotkin in race conditions. Kubica’s chances would surely fade if he does not get an opportunity to prove himself this year. Either way, he can be considered far down the pecking order, along with F2 frontrunner Artem Markelov.

All change at Toro Rosso and Sauber?

Toro Rosso could have two new drivers next year. Daniil Kvyat is understood to be closing in on a shock return to the team and Red Bull programme that unceremoniously dumped him from F1 last year. The ousted Stoffel Vandoorne could be an option given his knowledge of Honda’s power unit, but Red Bull has made clear its intentions to promote from its own stable, despite a current lack of options available in its junior pool with Dan Ticktum not quite yet in a position to step up due to a lack of superlicence points.

Brendon Hartley’s future beyond this year is uncertain and he told that he feels he is “fighting” for his F1 career. Speculation has linked Formula E champion and current Red Bull and Toro Rosso reserve Sebastien Buemi with a seat at the team he made his F1 debut with, though Christian Horner appeared to pour cold water over such a move following Friday practice at the Singapore Grand Prix.

An outside bet could come in the shape of former Red Bull junior Alexander Albon following an impressive F2 campaign that has seen the British-Thai driver emerge as an title contender. Alternatively, ex-Manor and Sauber driver Pascal Wehrlein is now a free agent following his release from the Mercedes junior programme that is hampering Ocon’s hopes of finding a seat outside of teams with an alliance to the German manufacturer.

Having witnessed the rapid progression of Max Verstappen and Pierre Gasly to the Red Bull senior team, the shortlist of drivers vying for a seat at Toro Rosso has steadily grown in recent weeks as other moves have fallen into place up and down the grid.

After Raikkonen’s surprise return to Sauber, one seat remains alongside the Finn. It appears to be a straight shoot-out between Marcus Ericsson and Scuderia junior Antonio Giovinazzi given Vandoorne has already been ruled out of linking up with his former ART GP2 boss Frederic Vasseur. Ferrari team principal Maurizio Arrivabene provided an update on Giovinazzi's future in Singapore, adding he expects a decision to be made in the coming weeks.

Bringing in Giovinazzi, who contested two grands prix for Sauber at the start of 2017 as stand-in for the injured Wehrlein, would go some way in securing the futures of both Ferrari’s long-term prospects, as well as feeding Giovinazzi onto the grid to learn the ropes alongside the experienced hands of Raikkonen at the Swiss squad that is becoming increasingly-swayed by the Scuderia’s influence.