Five-time world champion Lewis Hamilton has threatened to quit Formula One if organisers keep adding races to an already congested calendar.
Hamilton secured his latest drivers' title with a fourth-placed finish in Mexico last time out, the 19th stop of the 2018 campaign.
Brazil and the United Arab Emirates are the final two races of the season, the latter coming on November 25, eight months after the curtain-raiser in Melbourne.
The 2019 schedule also has 21 races but will run from mid-March to early December, while owner Liberty Media is keen to add further grands prix.
In 2020, the first Vietnam Grand Prix will take place, while there have been suggestions an extra race in the United States – in Miami – could be added.
Hamilton is not a fan, though, and has suggested he would leave the sport should further additions be made.
"I am not going to be here if it gets to 25 races, that's for sure," said the Mercedes ahead of the Brazilian Grand Prix.
"It already feels like are on race 25 this year, so I don't think that's a good thing. I think 18 was probably the best back in the day.
"I'm someone who really loves racing but the season is long. It's a lot of commitment for all of us and a lot of time away from families, and the seasons are getting longer and the off time is getting shorter.
"All I can do is speak is for myself. The turnaround is so short, you start preparing for your next season often as soon as the season is done. Getting your mind turned. That's very difficult. Then you have to find a way of switching off and recovering at the same time."
19 de abril 2019
|We always expect something special from Messi – Valverde|
|The O-Line bond behind two Heisman Trophies - Dru Samia & Ben Powers talk protecting Baker Mayfield|
|Super Saints thrash sorry Wigan as Leeds Rhinos climb off the bottom|
|Ramsey could return in two weeks, says Emery|
|Valverde surprised by Coutinho controversy|
|Sexton, Mako Vunipola return for European Champions Cup|
|Under-strength Hurricanes survive Sunwolves scare|
|Lingard admits top-four finish would be ´massive´ for Manchester United|
|Icardi planning Inter stay - agent Wanda Nara|
|Impossible to recreate Ajax model in Serie A – Spalletti|
|Elijah Holyfield set for NFL armed with fatherly advice and Georgia grounding|
|Guardiola ´delighted´ for Ajax boss Ten Hag|
|He can be an important player for us - Gattuso leaves door open for Silva|
|Medvedev stuns Djokovic to continue dream Monte Carlo run|
|Guardiola: Referees can still make mistakes with VAR|
|Te´o to depart Worcester Warriors amid rumours of Top 14 move|
|Odriozola suffers broken collarbone|
|Sheffield United 2 Nottingham Forest 0: Duffy sends Blades second|
|I really felt for them – Klopp sympathises with Manchester City´s VAR heartbreak|
|Champions League exit no title race advantage for Man City, says Guardiola|
|Mitchell magic seals golden-point win for Roosters|
|Kante: Chelsea not favourites for Europa League|
|Adelaide United 1 Melbourne Victory 0: Blackwood header snatches victory|
|Klopp applauds ´role model´ Salah after making Time magazine cover|
|Fabregas suffers calf injury ahead of PSG clash|
|Ronaldo is the future of Juventus - Allegri defends star after Champions League exit|
|Simeone: Costa issue is resolved|
|Khan always believed big nights would return as Crawford looms into view|
|Liverpool and Manchester City are miles ahead of the rest - Warnock|
|Wilder: Joshua fight is inevitable|
|There´s no other player like him - Rivaldo tips Messi for Ballon d´Or|
|Malone urges Nuggets response to ´hungry´ White|
|Fosu-Mensah returns to Man United from Fulham for knee surgery|
|Solskjaer claims some Manchester United stars ´need a reality check´|
|Brown lauds exceptional Simmons after Sixers take series lead|
|Maitland-Niles buoyed by Emery´s belief in Arsenal stars|
|Durant showed who he is – Kerr|
|Giroud will stay at Chelsea, insists Sarri|
|The big Friday Premier League quiz|
|Dodgers hold off Brewers|
|76ers win without Embiid, Warriors bounce back in big way|
|Knicks confident they will appeal to stars|
|Capitals´ Reirden heated after hit on ´defenseless´ Oshie|
|Brady, Edelman react to Gronkowski denting the Lombardi Trophy|
|Koulibaly not drawn on future after Napoli loss|
|Ancelotti backs Napoli squad despite Europa League disappointment|
|Ajax in Champions League semis is ´crazy´, says Vertonghen|
|Pochettino reflects on ´bad feelings´ during dramatic win|
|Embiid to miss 76ers´ game three against Nets|
|Lowry leads RBC Heritage, Johnson makes good start|
|Benfica boss Lage bemused by touchline dismissal|
|Arsenal favourites for Europa League - Marcelino|
|Milner hoping for third time lucky at Barcelona|
|This Week in US Sports: Lightning handed historic loss, Red Sox massively hungover|
|Emery expects Ramsey to be out for ´some weeks´|
|NFL Draft 2019: Should Cardinals take Murray or stick with Rosen?|
|It´s a big problem – Sarri baffled by Chelsea´s second-half woes|
|Hazard knock ´nothing serious´, hopes Sarri|
|Drop in intensity caused Chelsea´s Europa League fright – Giroud|
18 de abril 2019
|Focused Crawford welcomes Sugar Ray Leonard comparisons|
|Giants GM Dave Gettleman shuts down Josh Rosen trade talk|
|Cas hold off Wakefield to win thrilling derby|
|Arsenal saw off Napoli with spirit - Koscielny|
|Napoli 0 Arsenal 1 (0-3 agg): Lacazette stunner sees Gunners coast through|
|Eintracht Frankfurt 2 Benfica 0 (4-4 agg): Hutter´s men through on away goals after controversial Ko|
|Chelsea 4 Slavia Prague 3 (5-3 agg): Sarri´s men reach semis despite alarming second half|
|Valencia 2 Villarreal 0 (5-1 agg): Lato and Parejo set up Arsenal semi-final clash|
|Sharapova comeback delayed after Stuttgart withdrawal|
|Arsenal hit the front despite Ramsey blow|
|Liverpool to match Barcelona´s ticket prices and subsidise supporters|