Mercedes pair George Russell and Lewis Hamilton had contrasting fortunes during Friday’s free practice sessions for the Azerbaijan Grand Prix.
Russell needed a change of engine after early issues, which were compounded by further problems towards the end of the day.
After FP1, Mercedes spotted an anomaly in the oil analysis it was conducting on Russell’s engine. It then decided to swap in a different engine from his pool for FP2, which delayed him getting into the session.
The team is confident the removed engine can be used again and it will be fully analysed, but the understanding is the change was made for precautionary reasons rather than anything being obviously broken.
Russell was left looking across the garage for hope ahead of qualifying as he goes into the weekend on the back foot.
When asked if the reason for the issue had been found, Russell said: “For now, no. Not too sure exactly, we just knew we had to change the engine.
“So we had a problem after FP1, obviously delayed the session and then we also had a problem at the end of the session too.
“It wasn’t our finest Friday, that is for sure, but Lewis is looking quick out there so we know the car is capable of something strong, but once again Ferrari look really, really strong around here – they always seem to be fast in Baku.
“The problem was the engine in FP1, then at the end, it was actually a sensor failure, so we pitted because we thought we had a water leak but we didn’t.”
Even when he could complete some running, Russell was not happy with his performance and will need to rally himself to improve.
“It was feeling okay, it wasn’t feeling superb for me out there,” he added.
“I was struggling, I was definitely off the pace compared to Lewis. I was really struggling with confidence in the car and getting my tyres in the right window so I need to try and step up my game a little bit for tomorrow and try and close the gap.”
Hamilton, however, was feeling positive following his own performance as he ended FP2 in third, just 0.066 seconds off the pace of Charles Leclerc at the head of the field.
That has left the seven-time world champion looking cautiously optimistic of a good weekend in the Azeri capital.
“It was a really good day. I enjoyed today, I hit the ground running from the get-go and made incremental steps with the set-up – and for once felt like we didn’t have steps that we had to come back on, it was consistently building,” he said.
“I don’t know how my long run is compared to others but we didn’t get a huge amount of laps. Yeah, I think Red Bull seem pretty quick, as does the Ferrari, but we are there or thereabouts.
“On this day you don’t know what fuel loads everyone is on and often when we get to P3 or particularly when we get to qualifying everyone takes a step and we haven’t so far, we haven’t always.
“I think we will stay cautious and just try to do the best we can with what we have, I hope we are closer to the front than it seems maybe but we will find out tomorrow.”
