- Lewis Hamilton will race for Mercedes for the first time at Australian Grand Prix
- Red Bull's Sebastian Vettel aiming for a fourth consecutive drivers' championship
- Red Bull will face competition at the front of the grid from Mercedes, Ferrari, McLaren and Lotus
- Five Formula One rookies will race for the first time in Melbourne on Sunday
The 2012 Formula One championship went down in history -- just over 100 days ago -- as one of the most unpredictable and thrilling seasons in the sport's 64-year history.
Sebastian Vettel muscled his Red Bull to the checkered flag to deny Ferrari toreador Fernando Alonso the title at the very last race in Brazil -- by a mere three points -- to become the youngest triple champion.
Can 2013 deliver an even better spectacle? The signs are looking very positive as teams tackle financial reality ahead of major rule changes in 2014, a key driver makes a fresh start, new names line up on the grid and tires once again promise to provide an unpredictable excitement factor.
CNN World Sport takes you through the need-to-know stories before Sunday's season-opener in Australia.
1. Counting the cost
F1 has always been an expensive business but economic downturns across many countries -- including Great Britain where eight teams are based -- have pulled finances sharply into focus in 2013.
Top teams are spending as much as $375 million a year while those at the back of the grid spend around $75 million.
Look at it another way and a team like Marussia can spend $2 million a week compared to an estimated $1 million a day splashed out by the wealthiest teams.
F1 chief Bernie Ecclestone has proposed an annual budget cap of $250 million for 2014 but that won't help the small teams stay in business.
McLaren boss Martin Whitmarsh, who is also chair of the F1 teams' association, has warned that seven marques are already in "survival mode."
There has already been one casualty as Spanish team Hispania dropped out at the end of 2012 because of financial pressures, having not scored a point in three seasons.
2. Pay for a place
The issue of pay-drivers, who bring substantial sponsorship to secure a ride in F1, has also been highlighted in 2013.
Kamui Kobayashi, Timo Glock and Heikki Kovalainen all lost their seats because they didn't bring enough money to the table.
Even worse, Luiz Razia found the cash to take Glock's Marussia berth only to lose it two weeks before the start of the first race when his sponsorship deal hit trouble.
In a further dent to the balance sheets, the entry fee for a place on the F1 grid was increased by governing body the FIA this season. Teams now have to fork out a basic rate of $500,000.
On top of that it costs an extra $5,000 for each point the team won in 2012. Champions Red Bull were charged $6,000 a point, therefore paid at total of $3.3 million just to get on the grid to defend their titles.
3. All eyes on Hamilton
When it comes to the narrative of the season there is one name filling all the pages -- Lewis Hamilton.
A new era dawns for the 28-year-old, who begins his first season without the support of the McLaren team which guided him for the last 15 years.
When Hamilton signed for Mercedes last September it was a huge risk and, even worse, it looked like a huge mistake.
But six months on, it is shaping up to be Hamilton's best move since he passed Timo Glock in Brazil to win the 2008 world title.
The Silver Arrow was the fastest car in testing and got significant mileage on the clock too. If that preseason form translates to the racetrack, Mercedes will be a real contender.
The haunted Hamilton of recent times has gone -- and it's not only because he splashed out on a private jet, new tattoo and dog Roscoe during the break.
In an interview before jetting off for Australia he tellingly said: "It's nice to be somewhere you are really wanted."
Hamilton certainly has the chance to stand on his own two feet at Mercedes, but settling into a new environment with different procedures will inevitably lead to some less-than-perfect moments. It will be fascinating to watch.
4. Red Bull target fab four
Vettel has a clear plan for 2013: he wants to join Alain Prost as a four-time world champion and help Red Bull win a fourth straight constructors' crown.
Despite these grand plans, the energy drinks team lacked fizz in preseason testing, leaving predictors of form flummoxed and frustrated.
Vettel's fastest lap in Barcelona was two seconds slower than the quickest overall time set by Nico Rosberg for Mercedes.
But Red Bull rarely show their hand in the winter, disguising lap times with higher fuel loads and wheeling out screens in the pit lane to stop rivals taking a peek at designer Adrian Newey's latest machine. The RB9 is an evolution of the car which has dominated the last three seasons and it has looked lithe and strong on track.
Even if Vettel and teammate Mark Webber start the season off the pace, as they did last year, Red Bull have proved they have the resources to fight back and win both titles -- and will still go into 2013 as the team to beat.
5. Red Bull's rivals
Ferrari, McLaren, Lotus and now Mercedes are all expected to go wheel-to-wheel at the front of the 2013 field.
Ferrari say their car is "200 times better" than the much-criticized 2012 model and, with a new aerodynamic upgrade coming for Australia, Alonso will relish taking the challenge to Vettel over all 19 races.
McLaren and the English team's new de facto No. 1 Jenson Button are not yet 100% happy with the new version of the car which won the last race of 2012 at Interlagos.
The MP4-28 looks fast but inconsistent. There have been teething troubles for the team's risky new design philosophy -- which includes a switch to pull-rod front suspension -- but McLaren are gambling on their new concept bringing big performance gains as the year goes on.
After a breakthrough win in 2012, Lotus will also be in the mix and targeting a place in the top-three teams.
Drivers Kimi Raikkonen and Romain Grosjean showed flashes of pace in testing but they did not complete many laps, which means reliability could still be an issue.
Mercedes completed 12 days of testing with the quickest car, ticking off the second highest amount of miles among the teams, which is an important part of race preparation.
There is still some skepticism over whether Mercedes -- a second off the frontrunners' pace at the end of 2012 -- have made a big leap forward in performance.
But equally there is optimism Hamilton and his old karting teammate Rosberg have a genuinely fast car capable of fighting for race wins.
6. Rookies to watch
There are five new faces on the grid this season -- Esteban Gutierrez (Sauber), Valtteri Bottas (Williams), Giedo van der Garde (Caterham), Jules Bianchi and Max Chilton (both Marussia).
All five have something to prove, but Bottas and Bianchi could announce themselves as real talents.
Williams snapped up Bottas three years ago, and the real racing team reckon they've got a real racer to carry them back to the front of the grid. The Finn, 23, is nicely embedded with the team and should score points quickly.
Bianchi has also had good breeding. The Frenchman has been part of Ferrari's driver academy since 2010 and was a tester for the Italian marque and Force India.
His experience with two quality teams should help him settle in quickly, but points-scoring with Marussia -- which ended last season empty-handed and 11th out of 12 on the grid -- will be difficult.
7. Technical rule changes
The rules governing car design are stable this season, which means most cars will be an evolution of what was on track in 2012.
The biggest change is that the drag reduction system (DRS) -- a moveable flap on the rear wing that flips open to increase straight-line speed -- can now only be used in designated zones at each circuit.
Many teams, and in particular Red Bull, had used it freely in practice and qualifying to increase their lap times. They won't be able to do that this year.
Teams can also no longer use DRS to affect other aspects of car performance -- a trick pioneered by Mercedes in 2012.
Flexible front wings had also been used by some teams -- Red Bull were usually under scrutiny -- to increase the aerodynamic flow of the car. However, a new ruling says front wings can now only bend by 10 millimeters, and tougher load tests will make sure teams are sticking to the rules.
What they can do, however, is add a "vanity panel" to the top of their car to hide the unsightly stepped noses.
8. Burning rubber
Tires are once again the biggest unknown for the teams heading into 2013.
Pirelli's new rubber is softer and the tire structure is more flexible with reinforced shoulders. A set of 2013 tires adds an extra 2 kilograms in weight, so the minimum weight for each car has increased to 642 kg.
Lap times on the 2013 tires are expected to increase by around half a second a lap. At the Barcelona circuit, which hosts the Spanish Grand Prix, many cars set lap times in testing this month that were quicker than pole position for the 2012 race.
Pirelli also wants to make sure teams need to pit at least twice during the race.
Tire degradation was mixed during testing but the colder temperatures in Spain mean performance there is not an exact benchmark for the warmer climes coming up in the first two races in Australia and Malaysia.
Pirelli effectively pays to supply tires to the F1 grid in a negotiated deal which also include track-side advertising. The teams also pay it a small contribution, but the bulk of the bill for the season's 36,000 spheres of rubber is picked up by the tire supplier.
The Italian company is now entering the final season of its three-year contract as F1's official tire supplier. Pirelli says it is intends to carry on -- but only if the financial conditions are right. A decision may be made in the first quarter of 2013.
9. One eye on 2014
While uncertainty exists about the tire supplier's future involvement, major rule changes for 2014 present a financial and technical headache for F1's teams.
Next season they must use six-cylinder turbo engines with a greater share of power gathered from kinetic energy recovery systems.
But with change comes opportunity, and that is why many teams -- especially those who don't expect to be at the sharp end of the championship -- have already shifted a large share of their resources to the development of next year's car.
Until then, the mighty V8 engines look set to power a battle royale when the 2013 season roars into life in Australia this weekend.