Norris had been running third in the lead train of cars during the second stint of the Marina Bay race, as polesitter Carlos Sainz controlled the pace at the front to bunch the field up.
But Norris found himself promoted to second when George Russell ahead of him, and Lewis Hamilton behind him, were switched to medium tyres under virtual safety car on lap 44.
With the medium compound proving to be the optimum tyre, and both Mercedes suddenly lapping more than one second faster than Sainz and Norris, it quickly appeared as though the German manufacturer would charge through to take a spectacular win.
Stella, sitting on the pitwall at the time, believed Norris’ podium shot was gone when he saw Mercedes peeling off into the pits for their fresh mediums.
“When I saw them going onto sets of brand new mediums, I thought they're going to pass us,” explained Stella. “The new medium was the correct tyre for that situation, considering the stint length.
“We considered actually pitting, but we would be on a used soft [as Norris had no other tyres available] and we were nervous of 16-17 laps flatout on a used soft. So we decided to stay out. We would have pitted in case of a safety car, but not in case of the virtual safety car.”
Source: Autosport