RB boss' telling Daniel Ricciardo admission as Liam Lawson stars in US Grand Prix

RB team principal Laurent Mekies has admitted the team's handling of Daniel Ricciardo's sacking was "not ideal".

But the decision was vindicated when his replacement Liam Lawson finished ninth in Monday morning's (AEDT) US Grand Prix, which equalled the Aussie's best result of the season.

To make the feat even more impressive, Lawson did it from 19th and last on the grid. There was also only one retirement from the race.

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Mekies claimed Ricciardo was aware Singapore would be his last race, and that the two parties had chosen not to make a formal announcement.

"It was not ideal to go through the weekend in that way," he said.

"First of all for him, on a professional and on a personal matter, and for the whole team around him.

"Yes, Daniel was aware (it would be his last race in Singapore). We did have discussions before the weekend. For many different reasons, we chose together to go into that weekend without announcing. And from that point onwards, we had to deal with it.

"It's a decision that, in hindsight, we may or may not do differently."

The morning after the decision was announced publicly, Lawson admitted he'd formally known he would be in the car in Austin for a fortnight.

Having not raced anything in over 12 months, Lawson was thrown in the deep end in Austin but proved to the world he could swim with the best of them.

He was 13th in the one and only practice session for the weekend, just over a tenth behind teammate Yuki Tsunoda.

He had a lap time deleted in the second part of sprint qualifying, and would go on to finish the sprint race in 16th.

Already facing 60 grid positions worth of grid penalties for new car parts - he took over Ricciardo's allocations, rather than starting his own - he was third in the opening part of qualifying.

Starting off the back of the grid on the hard tyres, he made the most of a spin for Esteban Ocon which split and slowed the pack.

He then put moves on both Aston Martins and Pierre Gasly, and ran as high as seventh as he went long on his hard tyres before he made his one and only stop.

He emerged from the pits in front of teammate Tsunoda, much to the Japanese driver's chagrin.

"How does this happen? Tell me how does this happen?" Tsunoda complained on team radio.

Tsunoda had also picked up a five-second penalty for leaving the track and gaining an advantage - the same penalty that robbed Lando Norris of third place.

Tsunoda's bad afternoon was compounded by a clumsy spin at turn one on lap 41.

Red Bull team boss Christian Horner said Lawson's drive was that of a "veteran".

Lawson said he was "very, very happy" with his afternoon.

"It's always nice to be overtaking cars rather than being overtaken and defending," he told Sky Sports F1.

"To have the speed today was enjoyable, especially that first stint. To be able to overtake cars like that, I think we've struggled to do that as a team recently."

Many are tipping these final six races of the season to be an audition of sorts for Lawson to be promoted to the senior Red Bull team alongside Max Verstappen.

"The goal every weekend is points. I know they have an expectation on me, but at the end of the day, I've got an expectation on myself as well to do a job," Lawson said.

"I want to stay in Formula 1 and have a full time seat next year. These races are my key to doing that.

"From my side, I'm taking it weekend by weekend. This weekend we're strong. We need to now focus on Mexico.

"I'm well aware of the expectation they have on me, but at the end of the day, it's been like that since I was 16 years old as a junior. They've always put that pressure on us. So realistically it's no different to that."

The F1 season continues at Mexico City next weekend.