Kimi Raikkonen will leave Ferrari at the end of the season to pave the way for Sauber rookie Charles Leclerc to join Sebastian Vettel in the team's line-up for 2019.

The Italian manufacturer confirmed on Tuesday that 20-year-old Leclerc will replace the Finn, who turns 39 years old before the end of the current campaign, with the 2017 Formula Two champion graduating after an impressive first year in F1.

But in an immediate twist, Raikkonen posted a message on Instagram to announce that he will return to Sauber – the team he started his Formula One career with in 2001 – after the 2007 world champion signed a two-year deal.

F1 Italian Grand Prix Show all 17 1 /17 F1 Italian Grand Prix F1 Italian Grand Prix Italian Grand Prix Fans say goodbye to Fernando Alonso Getty F1 Italian Grand Prix Italian Grand Prix Italian fighter jets recreate the national flag at the end of the national anthem Getty F1 Italian Grand Prix Italian Grand Prix Lewis Hamilton prepares for the start of the Italian Grand Prix AP F1 Italian Grand Prix Italian Grand Prix Kimi Raikkonen locks up as he leads the field into turn one. AP F1 Italian Grand Prix Italian Grand Prix Brendon Hartley is forced to retire on the opening lap. AFP/Getty Images F1 Italian Grand Prix Italian Grand Prix The safety car was deployed at the start of the second lap. REUTERS F1 Italian Grand Prix Italian Grand Prix Lewis Hamilton briefly took the lead from Raikkonen before the Ferrari fought back. AP F1 Italian Grand Prix Italian Grand Prix Kimi Raikkonen chose to pit much sooner than Hamilton AP F1 Italian Grand Prix Italian Grand Prix The Ferrari fans were delighted to see Raikkonen out in front Getty Images F1 Italian Grand Prix Italian Grand Prix Daniel Ricciardo and Pierre Gasly collide in turn one. AP F1 Italian Grand Prix Italian Grand Prix Pierre Gasly bounces over the second turn. AFP/Getty Images F1 Italian Grand Prix Italian Grand Prix Hamtilon pitted much later than Raikkonen to come out on fresher tyres. REUTERS F1 Italian Grand Prix Italian Grand Prix Lewis Hamilton crosses the line to win the Italian Grand Prix. REUTERS F1 Italian Grand Prix Italian Grand Prix Mercedes celebrates Hamilton's triumph at Monza. REUTERS F1 Italian Grand Prix Italian Grand Prix Hamilton was delighted with the victory after extending his championship lead. Getty F1 Italian Grand Prix Italian Grand Prix Hamilton leaps off his Mercedes to celebrate with his team. AP F1 Italian Grand Prix Italian Grand Prix Fans flood the Monza track following the Italian Grand Prix. REUTERS

Raikkonen, the fifth-most experienced driver in F1 history with 285 Grand Prix starts and 100 podium finishes to his name, wrote on Instagram: “Guess who’s back?! Next two years with @sauberf1team ahead! Feels extremely good to go back where it all began!”

Sauber quickly confirmed the move that will see Raikkonen’s 18-year Formula One career – which included two years away from the sport in 2010 and 2011 – continue next season. This will likely see him move to second in the list of most grand prix starts above Jenson Button, Michael Schumacher and the departing Fernando Alonso. Only Rubens Barichello remains out of his reach.

“The Alfa Romeo Sauber F1 Team is delighted to announce that Kimi Raikkonen will join the team from 2019. The 2007 Formula One World Champion has signed for the next two seasons,” a statement read.

“In his career, Kimi Raikkonen has secured 20 Grands Prix wins and 100 podiums, making him one of the most highly regarded drivers in the history of the sport. The Alfa Romeo Sauber F1 Team looks forward to the arrival of the Finnish driver, with whom the team shares the common goal of achieving ambitious results.”

Frédéric Vasseur, chief executive of Sauber Motorsport and team principal of the Alfa Romeo Sauber F1 team, added: “Signing Kimi Raikkonen as our driver represents an important pillar of our project, and brings us closer to our target of making significant progress as a team in the near future.

“Kimi’s undoubted talent and immense experience in Formula One will not only contribute to the development of our car, but will also accelerate the growth and development of our team as a whole. Together, we will start the 2019 season with a strong foundation, driven by the determination to fight for results that count.”

Kimi Raikkonen will leave Ferrari at the end of the year to join Sauber (Getty)

Raikkonen will leave Ferrari with fond memories, having won the 2007 world championship and taking nine wins with them in his first spell there between 2007 and 2009.

“Scuderia Ferrari announces that, at the end of the 2018 season, Kimi Raikkonen will step down from his current role,” a Ferrari statement read. “During these years, Kimi’s contribution to the team, both as a driver and on account of his human qualities, has been fundamental. He played a decisive role in the team’s growth and was, at the same time, always a great team player.

“As a world champion for Scuderia Ferrari, he will always be part of the team’s history and family. We thank Kimi for all of this and wish him and his family a prosperous future.”

Leclerc quickly announced that he had agreed to join Ferrari next year, and paid tribute to both his father, Herve Leclerc, who did in June 2017, and former Ferrari protégé Jules Bianchi, who tragically died in July 2015 after an accident at the 2014 Japanese Grand Prix.

“Dreams do come true... I'll be driving for @scuderiaferrari for the 2019 Formula 1 World Championship,” Bianchi wrote on Twitter. “I will be eternally grateful to @scuderiaferrari for the opportunity given. To @nicolastodt for supporting me since 2011. To my family.

“To a person that is not part of this world anymore but to whom I owe everything of what is happening to me, Papa. To Jules, thank you for all the things you learnt me, we will never forget you, and to all the [people] that supported me and believed in me.

Jules Bianchi, a close firend of Leclerc's, passed away in 2015 (Getty) (Getty Images)