Carlos Sainz's race was over before it really began after his Renault customer engine hit trouble on the formation lap, before stopping him shortly after the start.

Teammate Lando Norris looked set to take a well earned fifth spot before his engine lost power on the penultimate lap, stopping him at the start/finish line as he eventually dropped to 11th.

McLaren team principal Andreas Seidl said the team was frustrated to have lost the chance for a good points tally, as he said joint efforts were needed to fully understand what happened.

"It's disappointing for us to have two DNFs, with one driver not even being able to make the race start," explained Seidl. "At the same time the situation is on Renault's side as well.

"Renault is making a huge effort in order to bring power updates throughout the season so that's encouraging to see. But of course, [it is] disappointing to have all these penalties and the DNFs in the races.

"It is important that we have a transparent and open relationship there, and that we analyse the issues and try to solve them together."

Asked if the troubles on the older Spec B engine meant the team regretted not committed to race the Spec C engine instead, Seidl said: "We need to wait first, I don't think it's related. Again, it's speculating and we really need to see. I don't think it's related to the engine spec."

Seidl added that Norris' power unit was not at the end of its engine life, so should have had enough mileage to be used again.

McLaren says one of the key things it needs to understand from the Belgian GP weekend was why its pace in the race was so strong after a qualifying where it appeared to be on the back foot.

Seidl said: "Very interesting now to see the analysis in the next week, what the reason was that we could suddenly be the fourth-fastest car because we didn't expect that with the strategy we had on Friday and Saturday.

"We made a step with Lando in qualifying so we were only a tenth away from qualifying three, but I expected a different race."