After losing his Sauber Formula 1 seat to Ferrari prodigy Charles Leclerc and missing out on the vacancy alongside Lance Stroll at Williams, 2015 DTM champion Wehrlein is now weighing up whether to return to the tin-top series for what will be Mercedes' final year in the championship.

The German manufacturer's decision to quit DTM at the end of 2018 in favour of a Formula E entry prompted Wickens to join the Schmidt Peterson Motorsports IndyCar squad earlier this year.

That leaves a vacancy in the six-car HWA line-up that would likely be filled by Juncadella, who raced in DTM for Mercedes from 2013-16, should Wehrlein prefer to focus on securing a third driver role in F1.

It's understood that Mercedes is not keen to add a rookie to its line-up for its final season, meaning Formula 3 frontrunner Maximilian Gunther is set to miss out on a full-time DTM graduation.

However, Gunther could be a candidate for a DTM debut at Lausitz, where two Mercedes drivers – Edoardo Mortara and Maro Engel – have a conflicting Formula E race scheduled in Berlin.

A decision on where Mortara and Engel will race will be made based on their respective positions in both championships ahead of the clash.

Lucas Auer, Gary Paffett and Paul di Resta, who was also a candidate for the Williams F1 seat, will all remain on board for the full 2018 campaign.

Audi is set to run an unchanged line-up for the 2018 campaign, having signed two rookies – series champion Rene Rast and former LMP1 star Loic Duval – at the start of the 2017.

Mattias Ekstrom, Mike Rockenfeller, Jamie Green and Nico Muller will remain alongside the pair.

BMW has already announced it will add two rookies to its 2018 line-up, with F3 graduate Joel Eriksson and GT3 driver Philipp Eng replacing Tom Blomqvist and Aston Martin-bound Maxime Martin.