Williams reserve driver di Resta received a remarkably late call up just 90mins before qualifying after Felipe Massa - having been passed fit to compete in FP3 following dizzy spells after practice yesterday - decided he couldn't continue in his current state.
Massa felt unwell following Friday practice and went to hospital for precautionary tests. He was cleared to take part in Saturday's final session before qualifying but ended it early.
Amid concerns about Massa's fitness for what is usually a particularly physically demanding grand prix, Williams made a decision to call up di Resta as a substitute.
"It comes down to getting out there and seeing it yourself".
"I think if we had to have anyone in our auto, you're going to have total confidence with someone like Paul". "I'm standing by pretty close".More news: Flash flood watch extended for Las Vegas Valley
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"I'm sure there are some nerves there, he hasn't had much time to get ready, but I have utter confidence in him that if anyone can do this, Paul can".
"You're very anxious. Nervous but very excited. I haven't driven one of these cars for three-and-a-half years apart from 10 laps I did in a 2014 auto and you get thrown into qualifying which is the deepest of all deep, jumping off a cliff and seeing how you can fight for survival". It's a tricky little track. From that you carry all of Felipe's brake and steering wheel settings, everything you try and work through a weekend to do, but it is hard.
"You just have to get in the auto and do the best-possible job". There's no pressure out there.
He had already been informed of the situation the night before but Massa was then cleared to drive on Saturday morning and it looked like the crisis was over.
"I think he's more upset than anything else", Williams told Sky Sports on Massa's situation.
"The main thing is that Felipe's health is OK".