Pierre Gasly
Pierre Gasly and Carlos Sainz were teammates in 2017. In this picture, Gasly (L) and Toro Rosso's Spanish driver Sainz Jr. attend a press conference ahead of the Formula One Malaysia Grand Prix at the Sepang circuit near Kuala Lumpur on Sept. 28, 2017. ROSLAN RAHMAN/AFP/Getty Images

Daniel Ricciardo’s sudden change of heart to move to the Renault Sport F1 team despite having agreed terms with Red Bull Racing came as a shock to the Austrian team.

Red Bull team principal Christian Horner is said to have initially thought the Australian racer was joking when Ricciardo revealed to him over the phone last Thursday that he will be joining the French manufacturer in 2019.

Ricciardo held positive talks with Red Bull owner Dietrich Mateschitz during the Austrian Grand Prix and even revealed to the media during the British and Hungarian GPs that he was close to agreeing a new deal to remain with the Milton-Keynes based team for the foreseeable future.

However, it was not to be as the entire F1 world was shocked to hear that Ricciardo had held talks with Renault and McLaren and expressed a strong desire to leave Red Bull. On Friday it was confirmed that he will partner Nico Hulkenburg after agreeing a two-year deal worth around $26 million per-season.

Daniel Ricciardo
Daniel Ricciardo will be clad in the yellow overalls of Renault in 2019. In this picture, Daniel Ricciardo of Australia and Red Bull Racing prepares to drive on the grid during the Formula One Grand Prix of Hungary at Hungaroring on July 29, 2018, in Budapest, Hungary. Mark Thompson/Getty Images

Max Verstappen is now without a teammate at Red Bull and it remains to be seen if the team promote from within like they have always done or if they will take a risk and hire a driver from outside their Red Bull junior program.

There are a number of candidates available with nine teams yet to confirm their driver lineups for the 2019 campaign. Mercedes and now Renault are the only two teams to reveal their pairing for the forthcoming season.

The easy choices for Red Bull are Toro Rosso driver Pierre Gasly and Carlos Sainz, who is contracted to the Austrian team. But Fernando Alonso, who is keen to drive a race winning car before the end of his career is seen as a leftfield choice, while there are other drivers like Sergio Perez, who has experience at a top team and Kimi Raikkonen, who is yet to be offered an extension by Ferrari.

Pierre Gasly

The young Frenchman, who currently drives for sister team Toro Rosso, is everyone’s favorite to take over the vacancy alongside Verstappen, mainly because the team has always looked to their junior program when needing to fill a vacancy. Moreover, Gasly has impressed this campaign with some good drives at the Monaco Grand Prix, Bahrain Grand Prix and most recently at the Hungarian GP.

Another advantage Gasly possesses is the working knowledge of the Honda power unit, which will power the Red Bull team from 2019. He has been providing the Red Bull team information on the developments being made by the Japanese manufacturer and will already be in-tune with it going into the 2019 campaign.

Carlos Sainz

The Spaniard impressed when he was with Toro Rosso for three seasons, and after making it clear that he wants a step up, he engineered a move to Renault in 2018. He is spending the current season on-loan with the French manufacturers, but, the arrival of Ricciardo has left him without a drive for the next season.

Sainz is still contracted to Red Bull and could easily fill the vacancy as he has proven himself to be a competitive racer. But his relationship with Verstappen is said to be in the way of the Austrian team hiring him. The duo shared a slightly fractious relationship when they were paired together at Toro Rosso for one and half seasons. The Spaniard is linked with a move to McLaren to either partner or replace Fernando Alonso.

Fernando Alonso

The two-time F1 Drivers’ champion is guaranteed to bring a winning mentality and despite being 37-years-old, is one of the best drivers on the grid at the moment. However, he is in the latter stages of his career and will be demanding of the team to treat him as the lead driver.

It could certainly lead to friction as Red Bull are clear that they are building the team around Verstappen. Moreover, Alonso’s relationship with Honda is broken after their three disastrous years together at McLaren. The Japanese manufacturer are certain to have a say if Red Bull do consider the Spaniard, but it remains unlikely the Austrian team will take the risk.

Sergio Perez and Kimi Raikkonen

The Mexican driver is almost certain to remain with his current employers Force India, but if Red Bull were looking out for options outside their stable, Perez remains a competitive alternative. He has proven during his time in F1 to be a fast driver — evident by his numerous podium finishes and his one-year with McLaren has opened him to the workings of a big team.

Raikkonen, on the other hand, is a veteran of the sport and is currently driving his 16th season in F1. He is currently contracted to Ferrari until the end of the current campaign, and is yet to be offered a new deal. Reports suggested that the Italian team were planning to replace the Finn with young Ferrari academy driver Charles Leclerc, who has impressed for Sauber in his debut F1 season in 2018.

But there could be a change of heart and Ferrari retain Raikkonen for one more season after his impressive performances in recent races. If not he could be an alternative for Red Bull, as he does not come with too much baggage and still possesses the speed to win races.