After a short 16-week offseason, Formula One is back on track this week in Melbourne Australia.
Once again, the big question at the start of the season is: Can anyone dethrone Sebastian Vettel and Red Bull?
Vettel and Red Bull will attempt to win the drivers' and constructors' championship for the fourth consecutive year. The 25-year-old German is certainly the favorite to win the title this season, but his campaign for another championship might be just as tough, if not tougher, than it was this past year.
Fernando Alonso and Ferrari are starting off this season with much more optimism than they had one year ago, and Lewis Hamilton is set to begin his first season with Mercedes after spending the past six years with McLaren.
Following 12 days of pre-season testing in Barcelona and Jerez, Spain, Red Bull looks strong heading into the season-opening Australian Grand Prix, as Vettel and his teammate, Mark Webber, were among the fastest in testing. But Mercedes was the most impressive in Spain, with Nico Rosberg and Hamilton posting the quickest times in four of the 12 days. Ferrari, Lotus and McLaren weren't too shabby as well.
While testing was merely a dress rehearsal for the upcoming season and a chance for the 11 teams and 22 drivers on this year's F1 entry list, no one is quite certain who will perform the best throughout the year.
Drivers and teams are eager to arrive in Melbourne to find out who has the right stuff and who might be in trouble this season.
VETTEL'S BID FOR FOUR
After finishing the 2012 season only three points ahead of Alonso, Vettel became just the third driver in F1's 63-year history to win three successive world championships. Juan Manuel Fangio won four titles in a row from 1954-57, while Michael Schumacher, who retired from the sport for good at the end of last season, captured five straight championships from 2000-04.
One year ago, Vettel and Red Bull didn't exactly burst out of the gate, like they did at the start of the 2011 season, when he and the team won six of the first eight races. He finished second in the other two. Vettel's first win last year didn't come until the fourth round in Bahrain.
Vettel needed a late-season surge to help him win his third title in a row. He rebounded from a 39-point deficit by winning four consecutive grand prix (Singapore, Japan, Korea and India).
During preseason testing, Vettel was pleased with the performance of Red Bull's car for 2013, the RB9.
"We managed to test quite a lot, but we also know that there is still a lot of room for improvement," Vettel said. "All in all, I am fairly happy with how everything went in these last weeks. The team did a great job with the car, and both Mark (Webber) and I felt comfortable right away.
"We haven't come across any big problems, and the smaller ones have been dealt with straight away. The RB9 has been so reliable that it's been a pleasure to drive. We learned a lot over the winter tests, and we'll be bringing that new knowledge with us to Australia."
The one big challenge that Red Bull and all other teams face heading into this season is the new Pirelli tire. This tire is heavier, but the compound is softer and faster than the previous one.
Based on testing, teams are uncertain how the tire will perform in Melbourne. Vettel said after his last day of testing that teams will need more time to better understand the tire. He also thinks it will be difficult to predict what will happen in the Australian GP.
"I think it is impossible for all of us to read the pace of the cars and to make out any favorites," Vettel said.
Other than the tire change, there are no significant changes to the F1 technical regulations this year.
WHO HAS A SHOT AT STOPPING VETTEL, RED BULL?
Even though he came up short of winning his third F1 title, Alonso claimed last season was the best one of his career. Alonso, who won back-to-back championships from 2005-06, scored three wins and 13 podium finishes this past year. The Spaniard finished either second or third in the last five grand prix, but it wasn't good enough for him to beat Vettel for the title.
Before the start of last season, it looked as though Alonso and Ferrari were headed for trouble when the Italian team endured numerous performance and reliability issues with its cars in testing. The problems were quickly rectified, as Alonso won the second round in Malaysia.
In this year's preseason testing, Ferrari drivers were second and fourth fastest overall in Barcelona and Jerez, respectively. Alonso and his teammate, Felipe Massa, who was retained by team for this season, each had a day of being on top of the time charts.
Alonso admitted there is still more work to be done on Ferrari's F138, but he is very optimistic about this season.
"Last year was the best year of my career, and I was very happy with the performance, but I think this year will be better," Alonso said. We have a better starting point, and I have learned from some of my mistakes from last year.
"The trust, confidence and motivation are better than any other year, and pit stop wise, with starts, all these things, we are constantly learning. I have prepared better. I am better than last year."
After competing in the World Rally Championship from 2010-11, Kimi Raikkonen had a remarkable comeback in F1 this past year. The Lotus driver finished third in points and won the Abu Dhabi Grand Prix. It was his first win since the 2009 Belgian Grand Prix, when he drove for Ferrari.
Can Raikkonen carry over his momentum from last season and be a perennial threat for this year's championship?
"Hopefully, but it's so difficult to say from testing," Raikkonen said. "Let's see what happens in Melbourne. Hopefully, we can be fast in the first races and have a good start to the year."
Raikkonen led the way on the final day of testing in Jerez last month. His teammate, Romain Grosjean, was quickest on the second day there. Grosjean was also the fastest in one of the test sessions in Barcelona.
Even though he finished fifth in point standings, Jenson Button ended last season on a high note by winning the Brazilian Grand Prix. Button's momentum could very well continue after McLaren has spent a lot of time and effort during the offseason to improve the reliability of its cars. McLaren experienced numerous mechanical and reliability issues with the MP4-27 this past year, so the team has done a major overhaul with its new car, the MP4-28.
"In terms of the car itself, the MP4-28, it's very good," Button said. "We have had a few issues, which have set us back a little bit, but I feel that the car in Melbourne will be strong. But it's just really doing enough laps in it before Melbourne that's really the key to feeling confident before we wheel the car out of the garage on Friday practice."
Button was the quickest on the first day of testing in Jerez. He has won the F1 season-opener in three of the previous four years.
Four drivers who competed in F1 last year are with a different team this season. Hamilton has replaced Schumacher at Mercedes after Schumacher spent the last three years with the team. Hamilton has fit in well with Mercedes, as he recorded the quickest time in day three of testing in Barcelona two weeks ago.
"There's still a lot of work ahead of us to get to where we want to be, but the team is doing a great job," Hamilton said. "It's been really nice to get to know everyone in the garage and how they work together over the past few weeks. The reliability, the mileage and the step-by-step improvements that we have achieved during the three tests are all very encouraging."
Hamilton and his teammate, Nico Rosberg, posted the overall first and third quickest times in the preseason tests.
Sergio Perez took over Hamilton's position at McLaren after the Mexican spent his first two F1 seasons with Sauber. Perez looked strong in his long-run tests and had the best time on the second day in Jerez.
"I think everything is going in the right direction, so it is quite important for us to keep going and keep progressing always in the right direction," Perez said.
Nico Hulkenberg left Force India and moved over to Sauber, while Charles Pic joined Caterham after his rookie season with Marussia.
After a year without a ride, Adrian Sutil returns to Force India this season. Sutil finished ninth in the 2011 point standings but failed to keep his seat at Force India for the following year.
With the demise of HRT, F1 will return to a 22-car grid for the first time since the opening rounds of 2008.
This season will feature five rookies.
Esteban Gutierrez, who finished second in the 2012 GP2 Series point standings, will pair with Hulkenberg at Force India. Valtteri Bottas is in Williams' driver lineup this season after serving as the team's test and reserve driver last year. Bottas will be teammates with Pastor Maldonado, who claimed his maiden F1 win in the Spanish Grand Prix last May.
Giedo van der Garde will drive for Caterham after he spent the past season as that team's reserve and test driver. Rookies Jules Bianchi and Max Chilton make up Marussia's driver lineup.
The full 2013 F1 entry list of constructors and drivers is as follows:
1 Sebastian Vettel (Germany) 2 Mark Webber (Australia)
3 Fernando Alonso (Spain) 4 Felipe Massa (Brazil)
5 Jenson Button (Great Britain) 6 Sergio Perez (Mexico)
7 Kimi Raikkonen (Finland) 8 Romain Grosjean (France)
9 Nico Rosberg (Germany) 10 Lewis Hamilton (Great Britain)
11 Nico Hulkenberg (Germany) 12 Esteban Gutierrez (Mexico)
14 Paul di Resta (Great Britain) 15 Adrian Sutil (Germany)
16 Pastor Maldonado (Venezuela) 17 Valtteri Bottas (Finland)
18 Jean-Eric Vergne (France) 19 Daniel Ricciardo (Australia)
20 Charles Pic (France) 21 Giedo van der Garde (Netherlands)
22 Jules Bianchi (France) 23 Max Chilton (Great Britain)