Gallery: F2's 18-inch tyre era begins in Bahrain

Sunday morning's opening test session provided a first glimpse of the Formula 1 feeder series' familiar Dallara F2 2018s fitted with their new wheels, which are set to be adopted by F1 in 2021, as well as a slew of new liveries for the 2020 campaign.

Louis Deletraz, who has moved to the Charouz squad for the new season, set the pace with a best lap of 1m45.583s, edging out former Carlin teammate Nobuharu Matsushita - now driving for MP Motorsport - by a scant 0.025s.

Third-fastest was Jehan Daruvala (Carlin), the newest recruit to the Red Bull junior scheme, followed by Brazilian pair Pedro Piquet (Charouz) and Felipe Drugovich (MP).

Ex-Williams F1 racer Sergey Sirotkin, deputising for the absent Christian Lundgaard at ART Grand Prix, was seventh-fastest, sandwiched by DAMS pair Sean Gelael and Dan Ticktum.

See below for a selection of images from the first morning of running during the test, which spans three days and also features FIA Formula 3 on-track action.

Sean Gelael, DAMS

Sean Gelael, DAMS Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Robert Shwartzman, Prema Racing

Robert Shwartzman, Prema Racing Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Marcus Armstrong, ART Grand Prix

Marcus Armstrong, ART Grand Prix Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Jehan Daruvala, Carlin

Jehan Daruvala, Carlin Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Marino Sato, Trident

Marino Sato, Trident Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Giuliano Alesi, BWT HWA Racelab

Giuliano Alesi, BWT HWA Racelab Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Guilherme Samaia, Campos Racing

Guilherme Samaia, Campos Racing Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Guanyu Zhou, UNI-Virtuosi

Guanyu Zhou, UNI-Virtuosi Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Nikita Mazepin, Hitech Grand Prix

Nikita Mazepin, Hitech Grand Prix Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Pedro Piquet, Charouz Racing System

Pedro Piquet, Charouz Racing System Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Mick Schumacher, Prema Racing

Mick Schumacher, Prema Racing Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Felipe Drugovich, MP Motorsport

Felipe Drugovich, MP Motorsport Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Yuki Tsunoda, Carlin

Yuki Tsunoda, Carlin Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Jack Aitken, Campos Racing

Jack Aitken, Campos Racing Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Sergey Sirotkin, ART Grand Prix

Sergey Sirotkin, ART Grand Prix Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Roy Nissany, Trident

Roy Nissany, Trident Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Artem Markelov, BWT HWA Racelab

Artem Markelov, BWT HWA Racelab Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Dan Ticktum, DAMS

Dan Ticktum, DAMS Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images

Louis Deletraz, Charouz Racing System

Louis Deletraz, Charouz Racing System Joe Portlock / Motorsport Images

Joe Portlock / Motorsport Images