Five red flag stoppages on the final morning are not enough to prevent George Russell posting the fastest time of the week.

Though there remain four hours of running, this afternoon will see the Spanish track artificially dampened in order that drivers can experience Pirelli's new wet tyres, therefore Russell's best of 19.233 will not be beaten.

The smooth, no-incidents of Wednesday seemed a lifetime ago as the red flags were waved for Fernando Alonso, Pierre Gasly, Guanyu Zhou twice and finally Sebastian Vettel over the course of the four-hour session.

Alonso's stoppage was down to a hydraulics issue which subsequently saw Alpine bring its test to a premature close.

"After further investigations in the garage following Fernando’s on-track stoppage earlier this morning, the team can confirm the issue was a problem with the hydraulics," said the French outfit. "A minor sealing issue led to a fire in the back of the car.

The team has successfully completed 266 laps during the three days of the shakedown. Repairs on the car will continue, and as a result we won’t be running for the remainder of the day. We look forward to be back in action at the next test in Bahrain."

Gasly's red flag was due to the Frenchman crashing at Turn 5, while a very, very big spin for Zhou left the paddock seeing red, shortly after which the Chinese driver suffered a technical issue and parked up on the pit straight.

The final red came around a quarter of an hour ahead of the lunch break, Vettel stopping on track with a suspected engine issue.

Apart from that it was a pretty uneventful morning, though a number of teams, most notably Ferrari, Mercedes and Williams are still suffering from porpoising. Indeed, Leclerc's bobbing F1-75 was clearly visible on the main straight.

With an eye on this afternoon's wet test, Williams took the rare decision to swap its drivers around mid-session, the Grove outfit intending to do the same thing this afternoon.

Though the porpoising remains an issue, Russell and Mercedes will be happy to have topped the timesheets and completed the most laps this morning.

Max Verstappen had a quiet, uneventful morning, but completed 58 laps on his way to posting the second best time.

While Alpine will be hugely disappointed to have had to end its test early, spare a thought for Haas where Nikita Mazepin completed just 9 laps having suffered a suspected oil leak.

This comes at a time the American team has admitted to having to have serious thoughts about its continued involvement with Russian sponsor Uralkali, whose branding was removed for the final day of running.

At a time F1 has axed Russia's round of the 2022 season, the withdrawal of Uralkali's backing could well be disastrous for the American outfit.

Check out our Friday gallery from Barcelona, here.