Red Bull team principal Christian Horner cut a subdued figure after arriving in Bahrain for the first day of Formula 1 pre-season testing.

Horner is currently under an internal investigation into 'inappropriate behaviour' - allegations he strongly denied to talkPORT last week.

The long-time F1 team principal said 'it’s business as normal' during the launch of the RB20 challenger in his first public appearance.

Horner lived up to that mantra for his new car's first time on track having arrived at the Bahrain International Circuit on Wednesday.

The 50-year-old was pictured alongside fellow Red Bull technical officer Adrian Newey, as the pair got set to prepare for testing.

Horner was later seen in high spirits while speaking to Red Bull's three-time world champion Max Verstappen amid reports that their relationship had become strained.

Though Horner's smile vanished when TV cameras attempted to zoom in on him after Wednesday's opening session had begun.

The longest-serving principal on the grid was captured awkwardly moving behind the cover of Newey as he popped up on the big screen.

The move caused a stir among fans, with Drive to Survive favourite Horner usually more than comfortable in front of the cameras.

One said: "Lurking from attention", while another joked: "His whole career is based on hiding behind Newey!"

Red Bull have been urged to conclude the investigation into Horner sharply, or risk it overshadowing the start of their dual-title defence.

However, Red Bull advisor Helmut Marko has defended the timing of the company's investigation.

Speaking to Red Bull’s ServusTV channel about the Horner situation, Marko said: “As you know, this is an internal investigation.

“The sooner a result is available, the better because of course, rumours and other stories are bound to sprout due to the long duration.

“[But] I think Red Bull has reacted very well in this matter. The long duration of this investigation is not their fault.

“They are endeavouring to [have] a fair investigation and then react accordingly.”

Horner meanwhile told talkSPORT during an exclusive interview last week that his loyalty to Red Bull would prevent him from ever working for another team.

Horner has been the face behind the pit wall at Red Bull Racing since their arrival on the grid in 2005.