Hamilton, Mercedes thwarted by engine issue, Vettel fastest

Ferrari's SF1000 revealed (2:10)

Ferrari reveals its 2020 challenger, the SF1000, in Reggio Emilia, Italy. (2:10)

BARCELONA, Spain - An engine issue curtailed Lewis Hamilton and Mercedes' running on the penultimate day of Formula One's preseason tests, while Sebastian Vettel went quickest in the Ferrari.

With reigning champion Hamilton at the wheel in the afternoon session, Mercedes was uncharacteristically slow to emerge from the garage as work took place on the car. When he did finally hit the track he completed 14 laps before the car ground to a halt at Turn 6 of the Circuit de Catalunya.

The stoppage was caused by an oil pressure anomaly, which made the engine shut down as a precautionary measure. The team was still investigating the issue when it confirmed the car would not return to the track before the chequered flag fell at 6pm local time.

Hamilton's teammate, Valtteri Bottas, had completed 47 laps before lunch. His stint was not without drama either, as he ran wide at Turn 5, but managed to avoid damaging the car against the wall.

Despite being comfortably quickest in terms of lap times so far and top of the mileage charts, there have been lingering reliability issues for the world champions. The manufacturer's team suffered an electrical problem last week, while customer team Williams has had three different issues with its Mercedes engines so far.

Thursday was Mercedes' least productive day of preseason. It is uncommon to see the world champions at the bottom of the mileage charts on a day of preseason testing. Last year's backmarkers, Williams, led the way in that category, with 2020 rookie Nicholas Latifi completing 160 laps.

How did Merc's rivals fare?

Sebastian Vettel led the way on a 1:16.841 for Ferrari, but that's still over a second shy of the benchmark set by Bottas in the Mercedes last week. Vettel's headline time was set on the 'C4' compound rather than the 'C5', which Bottas used for the preseason best, which explains some of the gap, but making accurate comparisons between times set at different times on different days, as well as unknown fuel loads, is never an easy thing.

The afternoon session saw focus on race simulations, meaning lots of high-fuel runs as mirrored what they would hope to do at a 66-lap Spanish Grand Prix at the same circuit in May. Ferrari was fastest of the teams completing a race simulation, but only had Racing Point, Haas, McLaren and Alfa Romeo for competition due to Hamilton's engine issue.

Bottas was not the only driver to have a dramatic moment. Italian driver Antonio Giovinazzi prompted a red flag mid-way through the morning session after spinning out at Turn 4 and going backwards into the wall, damaging the rear wing of his Alfa Romeo. He managed to get the car back to the garage but the repair job limited him to 92 laps overall.

Max Verstappen prompted another red flag shortly before the lunch break. The Dutchman lost control of his car on a wet patch on approach to Turn 4 and spun into a gravel trap, where his car got beached. Red Bull handed the car over to Alex Albon in the afternoon, who completed a series of high-fuel runs but without a race simulation to compare with Ferrari's.

Vettel prompted another red flag shortly after the session resumed, when he ran wide, spun and sprayed gravel across the track as he rejoined, forcing a stoppage so marshals could clean the circuit.

Final times:

1. Sebastian Vettel - Ferrari - 1:16.841 - 145 laps
2. Pierre Gasly - Alpha Tauri - 1:17.066 - 139 laps
3. Lance Stroll - Racing Point - 1:17.118 - 130 laps
4. Nicholas Latifi - Williams - 1:17.313 - 160 laps
5. Lando Norris - McLaren - 1:17.573 - 113 laps
6. Max Verstappen - Red Bull - 1:17.738 - 31 laps
7. Valtteri Bottas - Mercedes - 1:17.985 - 47 laps
8. Esteban Ocon - Renault - 1:18.013 - 37 laps
9. Kevin Magnussen - Haas - 1:18.225 - 111 laps
10. Alex Albon - Red Bull - 1:18.393 - 61 laps
11. Daniel Ricciardo - Renault - 1:18.395 - 59 laps
12. Antonio Giovinazzi - Alfa Romeo - 1:19.670 - 92 laps
13. Lewis Hamilton - Mercedes - 1:22.425 - 14 laps