Having declared after a front-row qualifying lockout that the pair would be free to fight for the victory, McLaren ordered Piastri to hold position behind Norris.
The local hero had caught the race leader and began applying pressure as the McLarens ran comfortable ahead of third-placed Max Verstappen.
“We had to go relatively soon to some back markers while the cars were close together and the conditions on track were still a little tricky, with intermediate tyres that were running down a bit in terms of their rubber on,” said Stella.
“And at the same time, we were receiving some updates on the weather forecast.
“So we had the going through the back markers and the update on the weather forecast that led us to close for a short period of time the internal racing between our two drivers until we had clarity as to the weather prediction.
“What this meant for how we should have used the tyres and then until we had closed the matter of overtaking the back markers.
“So once this was completed, and the weather was assessed, then we reopened the racing.”
Piastri was unable to find a way by Norris once the battle did resume, the Australian later noting his tyres were no longer in good condition.
“I think by the time we were free to race, that kind of killed my front left a little bit getting to the back of Lando,” Piastri explained. “So by that point, there wasn’t much I could do.”
Stella said the tyre condition and the fact the drivers were making small errors also contributed to the desire to pause the battle.
“I think in terms of retaining a consistent pace at that stage of the race, it was difficult, which is also one of the reasons why we wanted to pause the internal competition for a few laps,” he said.
“Both drivers were making little mistakes here and there, because I think as soon as you were putting the tyres on a slightly more wet portion, then you may have a sudden oversteer, you may have a little lock up because the front left was already quite worn.
“So I don’t know exactly what kind of issues he might have had in terms of pace in this phase of the race, but I suspect that it might have to do with these little issues that pushing at that level, in those conditions I’ve seen regularly on either of the drivers.”
Norris and Piastri eventually fell off the road when a rain shower hit just over 10 laps from the finish.
The Brit scampered back on track and pitted immediately for intermediate tyres before going on to win the race, while the Aussie spun and lost almost a lap stuck in the wet grass.
Piastri recovered to finish ninth, pulling a stunning around-the-outside pass on Lewis Hamilton in the dying moments.
