Carlos Sainz is poised to replace Sebastian Vettel at Ferrari with Daniel Ricciardo set to take the Spaniard's seat at McLaren.

Talks to seal the two moves are ongoing and no final agreements have been reached, but they are expected to be concluded and announced this week.

McLaren have been chasing Ricciardo for some time and his signing is a coup.

But they must release Sainz from his contractual obligations before signing the Australian.

Sainz had been in negotiations to stay with McLaren beyond 2020 but the appeal of joining a top team has convinced him to move.

The teams and drivers have been in negotiations for some time and talks are understood to be in their final stages.

The domino effect in the driver market was triggered when negotiations over a new contract between Ferrari and Vettel failed.

Ferrari announced on Tuesday that the German four-time world champion would be leaving the team at the end of the season, which is currently on ice as a result of the coronavirus crisis.

Ferrari have identified Sainz as the ideal support driver for Charles Leclerc, whose starring performances in his first season with the team last year undermined Vettel's status and precipitated his departure when he was not prepared to accept diminished contractual terms.

Ferrari will envisage Sainz in the type of back-up role Valtteri Bottas plays to Lewis Hamilton at Mercedes - quick enough to be close to him and engage in battle with other front-runners but not the team leader.

Sainz, who previously drove for Toro Rosso and Renault before moving to McLaren last year, is likely to view the move as an opportunity to prove himself as a top-line driver.

He excelled in his first season with McLaren last year and his strong race performances have earned him the call-up from Ferrari.

What about Ricciardo?

Signing Ricciardo is a major boost for McLaren, who last year made impressive progress back to fourth in the championship after a dismal few years falling down the grid.

The Australian came close to joining them in 2019 when he left Red Bull, but in the end chose Renault because they were more competitive at the time.

But the two teams' fortunes diverged last year, with McLaren jumping up the grid and Renault's progress back towards the top stalling; in fact they fell behind McLaren to finish fifth in the championship.

Ricciardo has now decided that McLaren are a better bet for the future - a decision partly influenced by their switch to Mercedes engines for the 2021 season.

That is one of a number of significant decisions made by their new team principal Andreas Seidl, who has impressed with his no-nonsense approach since joining the team in May last year.

Who will replace Ricciardo?

Ricciardo's departure leaves a space at Renault alongside Frenchman Esteban Ocon, assuming the car manufacturer stays in F1 next year.

Renault are said to be keen to promote one of their young drivers to the role but Vettel and double world champion Fernando Alonso have been mentioned as possible contenders.

Alonso said at the end of last year that he would consider a comeback to F1 after two years out, but he will have to weigh up whether he believes Renault will give him the competitive car he says he wants.

But he has fond memories of the team, having won both his world titles with them in 2005-6. He also returned there for a two-year period in 2008-9 after his move to McLaren turned sour in a tumultuous year alongside Lewis Hamilton in 2007 and before moving to Ferrari.

He has said he views the new regulations being planned for F1 as a chance for the field to be more competitive.

But these have now been delayed a year until 2022 as part of a package of changes to cut costs because of falling revenues from the truncated 2020 season.

That means Alonso - who turns 39 this July - would have to be prepared for a 2021 season likely in the upper midfield and it remains to be seen if he wants to go through that again after his four years in an uncompetitive McLaren from 2015-18.