Despite strong starting positions on the grid, and running in the top 10 early on, the double retirement meant a disappointing end to the Italian Grand Prix weekend.
Starting in 12th on Medium tyres, Lance made a good start and made his way past Nicholas Latifi early on in the first lap to sit in 11th position, before passing Sebastian for 10th.
With faster cars coming through the field, Lance was passed by the first of them – Carlos Sainz – to drop back into 11th.
The gap to Zhou Guanyu opened up, but Lance found himself defending a train of cars behind led by Soft tyre-shod Esteban Ocon after Sebastian had to retire, which brought out a Virtual Safety Car.
A difficult race day at the Italian Grand Prix
Lance and Sebastian were both fighting over the points-paying positions early on at Monza, but technical problems brought both of their races to an early conclusion. Lance retired late on, while an ERS issue ended Sebastian's race on lap 11.
Lance pitted at the end of lap 18 for Hard tyres, and a quick stop from the team allowed him to return to the track ahead of Yuki Tsunoda's AlphaTauri, but he was overcut by Ocon in the faster Alpine.
From there, he lost a position to Latifi, before gaining a position again after Kevin Magnussen stopped and then another when Fernando Alonso retired his Alpine.
He gained further positions when Mick Schumacher and Valtteri Bottas stopped, but on lap 39 the team called Lance in to retire as a precaution to save the engine.
We have to look at why it was so tricky for us on this track, and see what we can learn from that.
"We had some issues with the car, so we decided to retire to look after the engine.
"It is a shame that we were not able to be more in the mix this weekend, but that is sometimes how it is in F1.
"We have to look at why it was so tricky for us on this track, and see what we can learn from that.
"I think we will be more competitive in Singapore, which is a completely different circuit to here, in a couple of weekends."
Sebastian started the race from 11th position on Medium tyres, and displaced Latifi early in the first lap to sit in the points-paying positions.
He was passed by Lance on the second lap, and then by Sainz's faster Ferrari on lap six.
Sebastian was holding off Ocon in the faster Alpine when he started to lose power. He started to lose positions, and then retired with what was later diagnosed with an Energy Recovery System issue on lap 11, which brought his race to an end.
I noticed a drop in power beforehand, and then I was told to pull off the circuit. Overall, this was just a tough weekend for us.
"Unfortunately, we had an issue with the ERS and we had to stop the car.
"I noticed a drop in power beforehand, and then I was told to pull off the circuit. Overall, this was just a tough weekend for us.
"I was hopeful for a decent race, but we struggled for pace and then had the problem that forced our retirement.
"The atmosphere was fantastic, however, so a huge thank you to the fans for their support this weekend."
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