The two McLaren drivers were ruled out for excessive skid plank wear hours after the race had ended and the podium champagne been sprayed.
Mercedes boss Toto Wolff accuses rival Formula One engine manufacturers of ganging up to pressure the FIA over a proposed rule change, calling the controversy a "storm in a teacup" ahead of the new season.
Red Bull's Max Verstappen won the Las Vegas Grand Prix on Saturday but McLaren's Lando Norris had one hand on the Formula One title after finishing second and stretching his lead over teammate Oscar Piastri to 30 points.
Formula One will crown its champion in Abu Dhabi on Sunday with McLaren's Lando Norris and Oscar Piastri both seeking to dethrone Red Bull's Max Verstappen and deny the Dutchman his fifth title in a row.
Honda will return to Formula One in 2015 as McLaren engine partners, replacing Mercedes, sources close to the company said on Wednesday.
Honda's new V6 turbo hybrid Formula One engine will make its track debut at Silverstone on Friday in the back of a McLaren development car.
McLaren have no fears about losing Fernando Alonso to Mercedes after Formula One world champion Nico Rosberg's sudden retirement, the team's new executive director Zak Brown said.
McLaren driver Fernando Alonso will miss the Monaco Grand Prix in May in order to race in the Indianapolis 500, his team said on Wednesday.
Danish Formula One driver Kevin Magnussen is leaving McLaren after being informed by email on his birthday that the team had no place for him.
The Briton, the most experienced driver on the starting grid and 35 years old next January, will partner Spaniard Fernando Alonso in a lineup of champions.
The blue and papaya orange MCL34 car was unveiled by 34 team employees at the former champions' Woking headquarters before Sainz and 19-year-old British rookie team mate Lando Norris stepped up to admire it.
McLaren unveiled their new Formula One car on Sunday, certain it cannot be any worse than last year's but still unsure when they might get back to winning ways after their longest drought in decades. The former champions have not won a race since 2012 and finished last season, the first of a new partnership with Honda, ninth of the 10 teams with just 27 points compared to 703 for dominant Mercedes. The three years without a win is the team's longest barren stretch since their absence from the top step of the podium in 1994-96. "As we embark on the second year of our renewed McLaren-Honda partnership, all of us remain united in our purpose. That purpose is to develop our team towards our shared ambition: to win," said McLaren boss Ron Dennis. "We'll make no predictions as to when those wins will come," he added. The new MP4-31 car was presented online in a predominantly black livery with some prominent new sponsors in LVMH's sparkling wine brand Chandon and watchmaker Richard Mille replacing the departed Tag Heuer.
Formula One champions Mercedes expect to be beaten by Ferrari this season and also see McLaren catching up fast after a dismal 2015 for the Honda-powered team, engine head Andy Cowell said.
'McLaren car is 100 percent ready'
The Spaniard told reporters at the US Grand Prix, where he was ninth fastest in a wet first practice on Friday, that McLaren needed to find another two and a half seconds of pace to match Mercedes.
Media reports suggested the McLaren driver, whose wife is Japanese, was likely to announce at this weekend's Japanese Grand Prix that he would be leaving Formula One at the end of the year.
The 30-year-old, who could clinch his third world title within a matter of weeks, told British reporters at the Russian Grand Prix that he would always owe an immense debt to his former McLaren boss Ron Dennis.
McLaren drivers Fernando Alonso and Jenson Button stepped onto the Formula One podium for the first time this season on Saturday -- but only in jest after yet another qualifying nightmare in Brazil.
However, McLaren's David Coulthard warned Button not to be under any illusions.
Spain's double World champion Fernando Alonso and Britain's Jenson Button will drive for McLaren next season, the Formula One team announced on Thursday.
Fernando Alonso believes his McLaren team could have the best chassis in Formula One before long this year but the Spaniard also sees no end to champions Mercedes' domination after pounding out the laps in testing.
Formula One will have a record 24 races in the season that starts in Bahrain on Saturday.
A summary of sports events and sports persons, who made news on Wednesday
Brazilian Bruno Senna, nephew of the late triple world champion Ayrton, made his test debut for Honda in a new-look Formula One at Barcelona's Circuit de Catalunya on Monday.
The victory at Suzuka was the Dutch driver's 13th in 16 races this season and left him on the brink of a third world title.
McLaren will start the Formula One season without a title sponsor but still expect to have one this year, group chief executive Ron Dennis said.
McLaren drivers Fernando Alonso and Jenson Button will start last in Sunday's Belgian Formula One Grand Prix after being hit with heavy grid penalties for changes to their Honda power units.
Ferrari will present their new Formula One car online on January 30, a day after McLaren take the wraps off their Honda-powered challenger.
McLaren's Fernando Alonso is set to start Sunday's Formula One Malaysian Grand Prix from the back of the grid as he tries out an upgraded Honda power unit in practice on Friday.
McLaren Formula One driver Fernando Alonso will miss this week's final pre-season test in Barcelona after leaving hospital on Wednesday following a big crash three days ago.
Former world champion Fernando Alonso doubts he will make it onto the Formula One podium this season after also enduring his worst points tally last year, but has no immediate plans to retire.
Verstappen hustled his Honda-powered Red Bull around the popular figure-of-eight layout in one minute, 29.304 seconds
Fernando Alonso has credited McLaren with restoring the motivation he lost after five years at Ferrari.
Jenson Button hit back at Niki Lauda on Saturday after the Austrian Formula One great suggested the driver had told him he wanted to stay at McLaren next year and any uncertainty was about money.
Spain's Fernando Alonso will not race in next week's season-opening Australian Formula One Grand Prix on doctors' advice after a heavy crash in testing, his McLaren team said on Tuesday.
Fernando Alonso would be top of the list for Mercedes if Formula One champion Lewis Hamilton fails to agree a new deal with the team beyond this year.
Fernando Alonso made a troubled start to testing McLaren's new Formula One car
Jenson Button hailed Honda's latest power unit as a good step forward for McLaren after completing 121 laps and finishing fifth fastest on the second day of Formula One's final pre-season test on Wednesday.
"The comparison? I see still Ayrton winning the game because in the end Ayrton was such a charming guy and a personality. And obviously if someone loses his life and stays with us in the way of a legend, it's always something special. But I try to see it from a performance point and from a performance point, Lewis is going from one pole position to the next one and Lewis is going from one race win to the next one. Just like Ayrton did."
Fernando Alonso left the Brickyard on Sunday without a fairytale victory to cap his Indy 500 adventure but had no regrets as he prepared to return to his Formula One day job with McLaren.