McLaren will announce Carlos Sainz as Fernando Alonso's replacement later this week, ESPN understands, opening the door for Pierre Gasly to step up to Red Bull next year.
On Tuesday, McLaren confirmed Alonso will not continue in F1 beyond 2018, ending months of speculation about his future. McLaren had been making contingency plans for Alonso's departure and was in talks with Sainz and Daniel Ricciardo about a 2019 seat.
The Ricciardo talks were unsuccessful -- earlier this month the Australian announced his shock move to Renault for next year, taking Sainz's place as Nico Hulkenberg's teammate in the process. Sainz had been at Renault this year on loan from Red Bull having been unable to secure a step up to the senior team from Toro Rosso.
Ricciardo's imminent departure meant Sainz and Gasly were the favourites to fill the void. Sources have told ESPN that Sainz will be confirmed on a two-year deal at McLaren on Thursday, meaning Toro Rosso's Gasly looks set to be the man to make the jump and partner Max Verstappen in 2019.
The identity of Sainz's 2019 teammate remains unclear. If the out-of-form Stoffel Vandoorne is dropped by the team, junior driver Lando Norris would be a candidate. In the hours after the Alonso news, Norris tweeted a GIF with the word: "Interesting".
However, the Ricciardo switch has blown the driver market wide open, as has Lawrence Stroll's recent acquisition of Force India and the likely move his son Lance will make from Williams to that team next season. That will leave either Esteban Ocon or Sergio Perez looking for a race seat elsewhere next season.