Just as soon as we thought we had got to grips with Formula 1's silly season, Daniel Ricciardo has thrown an enormous curveball by ditching Red Bull for Renault in one of the most surprising moves of recent years. Rob Watts analyses the ripple effect the switch will have.

With a new Red Bull deal reportedly on the table, Ricciardo was widely expected to re-sign for another two years as his options with Mercedes and Ferrari appeared to close.

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Ricciardo's stock has risen considerably since joining Red Bull, and he's now considered one of the top drivers on the grid as well as being one of only six to have won races in the hybrid era.

So why trade that in for a team that has not secured a podium, never mind won a race, since buying out the Lotus squad in 2015?

Why is Ricciardo putting his trust in Renault?

That's a good question. Considering Renault have been unable to build a power unit capable of competing with the likes of Mercedes and Ferrari, Ricciardo's decision to commit the best years of his career to their works team seems a strange one.

But, when you break this down and consider all the elements, it begins to make sense.

Firstly, Red Bull clearly see Max Verstappen as their big hope for the future, and the bumper contract they gave him would suggest the team will be built around him in future, if it isn't already to some degree.

A driver with seven grand prix wins on his CV, who has only been outscored by Lewis Hamilton and Sebastian Vettel in the last two and a half seasons, shouldn't accept playing second fiddle to a guy ten years his junior - regardless of Verstappen's ability.

If he is to maximise his potential, and end his career with at least one title, he has to be the main man somewhere. If that can't be at Red Bull, then the time has come to move on.

Secondly, Renault have invested heavily in their factory, infrastructure and team personnel with the aim of returning the famous French marque to the front of the grid.

This has not gone unnoticed by their rivals, and there are many in the paddock who believe Renault could emerge as genuine title contenders in the coming years - especially when F1's new power unit regulations come into play in 2021.

Honda, on the other hand, are still yet to put forward a convincing case for being on the cusp of something great, and that might have played a part in Ricciardo's decision to jump.

While they appear to have progressed since their dismal spell with McLaren came to a premature end, it would be a major leap to believe they are capable of developing a title-challenging power unit in the next couple of years.

McLaren explained that their late switch to use Renault power for this season was made much easier by the French manufacturer's vast F1 experience. While Honda only returned to F1 in 2015 after seven years away, Renault have been ever-presents on the grid in some capacity since the turn of the decade and have powered Red Bull to race wins in eight of the past nine seasons.

Let's also remember, Red Bull had not yet committed to using Honda power when Verstappen re-signed until 2020. Would he have had the same level of confidence had he known?

Could this be Ricciardo's 'Hamilton' moment?

It could be, but it's very hard to predict. While Renault are undoubtedly making gains, neither Mercedes, Ferrari, or any other team on the grid are standing still.

When Lewis Hamilton left McLaren to join Mercedes at the end of 2012, no one believed he would go on to have the success that he has. He obviously knew something we all didn't, and that could be the case for Ricciardo too.

Whatever Cyril Abiteboul's sales pitch to him was, it obviously was enough to convince Ricciardo that they are going places. Let's be clear on one thing: Ricciardo is not going to Renault because he fancies helping them secure fourth place in the constructors' championship. He's going there to win.

Who will fill the vacant Red Bull seat in 2019?

After an impressive start to his F1 career, Pierre Gasly is likely to be the favourite replace Ricciardo at Red Bull, continuing the team's philosophy of promoting from within.

A year ago, Carlos Sainz would have almost certainly received the call had this situation arisen, but his decision to jump ship from Toro Rosso did not go down well within.

It's felt that Sainz showed a lack of loyalty for not seeing his Toro Rosso apprenticeship through, and Dr. Helmut Marko believes the Spaniard had forgotten too quickly who had given him his F1 shot in the first place.

As part of Sainz's loan deal with Renault, Red Bull has retained an option on him for 2019 but it's believed that expires in September, and he will be free to move on should he not be offered a deal with the senior team.

While Sainz's performances have clearly been a step up compared to Jolyon Palmer who he replaced at Renault, the experienced Nico Hulkenberg has proved a much tougher nut to crack than expected.

Had Sainz blown him away this year, he'd have strengthened his case for being Verstappen's teammate next season, but his failure to do so leaves Gasly as the favourite after a string of eye-catching performances that have quickly enhanced his reputation.

In a strange twist of fate, it would appear that the risk Sainz took to forge his own career path has massively backfired.

What does this mean for the rest of the grid?

Should Gasly get Ricciardo's seat, it will start a chain reaction that could affect almost every team still to finalise its 2019 line-up.

Gasly's promotion would likely mean a stay of execution for Kiwi Brendon Hartley who has struggled to adapt to F1 since his switch from sportscar racing last season. A seat alongside him would likely be occupied by either Red Bull junior Dan Ticktum (if he can get a Super Licence), or McLaren protege Lando Norris - who could be a makeweight in James Key's departure to Woking.

There's also a knock-on effect at Force India, where Esteban Ocon was expected to move to Renault next season, opening up a space for Lance Stroll to bring his Canadian sponsorship dollars to the team.

Ocon will now almost certainly stay, meaning Force India's financial situation is likely to determine whether they keep Sergio Perez or choose to take Stroll and his billionaire father's backing.

Sainz could be left short on options should the Red Bull door close on him, and he's highly unlikely to see a return to Toro Rosso as an attractive proposition given his desire to leave them just 12 months ago.

Therefore, McLaren could now be Sainz's best option. Team boss Zak Brown refused to deny when asked at the Hungarian Grand Prix that they were considering him for 2019, saying he would "certainly be high up the list for a race seat".

With Stoffel Vandoorne struggling badly for form and Fernando Alonso undecided on his future, Sainz to McLaren seems to be the next logical move to watch out for as the 2019 grid begins to take shape.

Who said silly season was going to be boring this year?