The 2021 Formula One season begins in Bahrain this weekend, with teams facing the longest ever 23-race season and Mercedes' Lewis Hamilton chasing a record eighth title. So what should F1 fans expect this season? Here's a look: F1’s technical overlord Ross Brawn has given the rules another shake up in a bid to improve the racing. Mercedes have won seven out of every 10 races since 2014 and fans desperately need a new script. Despite being forced into a money-saving holding pattern by the lingering pandemic, Brawn has come up with some clever tweaks. This year’s cars are heavier and wider, the tyres harder. Less testing has been allowed and at-race practice reduced. Car aerodynamics have been simplified (most significantly at the back) so the ‘dirty air’ effect from the giant rear wings that interferes with overtaking has been cut by 60 per cent. The signs are cars will be able to race harder and closer. The F1 driver deck has been shuffled far more than usual this year and that means new rivalries and new challenges. Having despatched Sebastian Vettel last year, Ferrari’s golden boy Charles Leclerc faces highly-rated Spaniard Carlos Sainz who raced Max Verstappen close at Toro Rosso. While four-time champ Sebastian Vettel joins Aston Martin looking for redemption after a disastrous time at Ferrari. He cannot afford to lose to the owner's son, Lance Stroll. Michael Schumacher's son <a href="https://www.thenationalnews.com/sport/f1/mick-schumacher-clinches-f2-title-ahead-of-move-into-formula-one-1.1123824">Mick makes his F1 bow</a> for Haas and cannot afford to be outgunned by fellow rookie Nikita Mazepin if he expects his Ferrari backing to pay off in a few years time. The box office figure of Fernando Alonso returns to F1 with rebranded Renault searching for his third world championship. Seems to have lost none of his startling speed <a href="https://www.thenationalnews.com/sport/f1/f1-driver-fernando-alonso-conscious-after-cycling-accident-1.1164672">despite a pre-season bicycle crash</a> which necessitated two titanium plates in his jaw. He pairs with youngster Esteban Ocon who was just 10 when the old warhorse won his first title. The longest season in the sport’s history starts on Sunday in Bahrain and ends just two weeks short of Christmas in Abu Dhabi. Twenty-three races is a milestone few teams ever thought they’d see. In fact, until recently the divorce rate was so high in the paddock, anything beyond a 20-race schedule was specifically banned. But with finances battered by the pandemic, the sport has been forced into a re-think. One of the most fascinating confrontations will be Max Verstappen versus Sergio Perez. At 31 and joining his fifth team in a decade, it’s make-or-break time for the Mexican. He was rated highly enough to be signed by McLaren as Lewis Hamilton’s successor only to be let go after one season. But he scored his first win last year in Bahrain. After a string of erratic drivers from their own academy, Red Bull say Perez’s form was too good to ignore. Whether he can live with Verstappen remains to be seen. Racing Point and Renault have gone through significant rebrands for 2021. Renault switch to their sport brand Alpine, much as Mercedes use AMG, with double champion Fernando Alonso at the wheel. Racing Point slips into the racing green colours of James Bond’s favourite car maker, Aston Martin, after ambitious Canadian billionaire Lawrence Stroll acquired both and united them. Which of the grid’s two chirpiest characters will stop smiling first as this rivalry heats up? Twenty-one year-old Lando Norris has a growing reputation on the line as he faces a career-defining year against proven winner Daniel Ricciardo. The Australian, tipped by many as a future champion, cannot afford a lacklustre year as he hunts a truly competitive drive. At 31, the clock is ticking. Formula One races at two new venues in 2021 across the longest season in the sport's history. Zandvoort in Holland returns after a 36-year absence while <a href="https://www.thenationalnews.com/sport/f1/saudi-arabian-grand-prix-a-first-look-at-the-jeddah-street-circuit-1.1186696">Saudi Arabia's night race on Jeddah's Corniche</a> is slated for the week before Abu Dhabi's finale. It will be the fastest street track on the calendar with average lap speeds topping 250kph. The fate of this entire season – and perhaps a few more to come – rests on the new Honda power plant and its surrounding hybrid technology. Pre-season testing suggests they have finally got one up on Mercedes but reliability is another matter. Performance in this hybrid era is a jigsaw of power sources from the ICE (internal combustion engine) to systems harvesting turbo heat and braking friction, as well as batteries storing it for invaluable extra boost. But can Honda really make all the parts work reliably enough across an exhausting 23 race season? F1 nervously embarks on one of the most dramatic experiments in recent years. Qualifying will move to Friday afternoon in favour of a Saturday 100km sprint race. The new race will have a small amount of points and decide the start order for the main race Sunday. Team talks this weekend in Bahrain will decide whether it will be trialed first at Silverstone in July, then Monza and later Brazil.