Red Bull and Daniel Ricciardo have agreed a deadline to decide on the driver's future at the team beyond 2018, says Helmut Marko

Ricciardo is one of several leading drivers currently out of contract at the end of the season and has made clear that, at 28 years old, the decision over where he drives from 2019 is the key one of his career so far.

The Australian said last week he expected contract talks with the team to resume "around April" and Marko, Red Bull's motorsport advisor, says both sides have put a timeframe on when they want those discussions to be concluded.

"We agreed with him a deadline," Marko revealed to Sky Sports News.

"So as soon as this deadline is over we'll tell you if it's yes or no."

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Ricciardo, who turns 29 in July, will enter those discussions knowing that team-mate Max Verstappen is already signed up to Red Bull until 2020.

But the former world champions have insisted they want to retain the line-up widely considered the strongest in F1 as they attempt to return to title-winning ways.

Ricciardo has won five races with Red Bull since being promoted to their senior team from Toro Rosso in 2014, outscoring his team-mates in all-but one season, but the Milton Keynes outfit have not mounted a championship challenge in that time.

However, with the new RB14 performing strongly in testing, hopes are higher than for some time that Red Bull will be closer to Mercedes and Ferrari when the new campaign kicks off on March 23.

"I think realistically around April things will start to be spoken," said Ricciardo at Test One. "After a few races, hopefully I win the first few and I can have a powerful say in what I do!"

Mercedes and Ferrari could also play a pivotal role in Ricciardo's thinking about his next contract.

While Sebastian Vettel is signed up to Ferrari until 2020 and Lewis Hamilton is soon expected to do likewise at Mercedes, the futures of the other drivers at the respective teams is less certain.

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F1's oldest driver Kimi Raikkonen has been on one-year deals at Ferrari since 2016 while Mercedes' Valtteri Bottas was handed only a single-season extension himself for this year after a mixed debut campaign with the Silver Arrows.

Ricciardo has also been linked with McLaren as an eventual successor to Fernando Alonso, although the Woking outfit's title drought stretches five seasons' longer than Red Bull's.

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