AP Sports Writer
AUSTIN, Texas (AP) -- Big changes are coming in Formula One in 2014. Not just the engines in the cars, but who will be driving them and for which teams.
With the 2013 drivers' and constructors championships wrapped up by Sebastian Vettel and Red Bull, Formula One heads into Sunday's U.S. Grand Prix in Texas and the final race next week in Brazil with an eye already on next year.
Kimi Raikkonen is leaving Lotus for Ferrari next season. Ferrari's Felipe Massa is switching to Williams, where Pastor Maldonado is out.
Sergio Perez is out at McLaren, and Red Bull's Mark Webber is leaving behind his frosty relationship with teammate Vettel by leaving Formula One to race with Porsche in the world endurance championship.
All that means a lot of upheaval in the cockpit at a time when the sport is about to make a major shift from the current 2.4-litre V8 engines to a 1.6-litre V6 turbocharged unit.
No driver change will be bigger than Raikkonen's move back to Ferrari, where the Finn raced from 2007-2009 and won the 2007 world title, the famed team's last championship. The move also matches him with two-time world champion Fernando Alonso.
Raikkonen is not driving the final two races of the season for Lotus after opting for back surgery. McLaren took on veteran driver Heikki Kavolainen to finish the season.
While Massa gets a new ride with Williams in 2014, the future is murkier for Perez and Maldonado.
Perez was a rising star when he signed with McLaren in late 2012, but the once formidable team has taken a hard fall this season with neither Perez or teammate Jenson Button earning a podium finish. McLaren's decision to dump Perez clearly wounded the 23-year-old Mexican just days before the race so close to his native country.
"It came as a shock to me because the team was always giving me good feedback, everything was pretty much settled down and I was going to stay with the team," Perez said. "But then something happened in the last few weeks ... It puts me in a very difficult position."
The move leaves Perez little time to find a new team in 2014.
"I want to stay in Formula One, but I will not stay in F1 just to stay," Perez said. "I think I have a lot to offer a team."
To replace Perez, McLaren opted to promote 21-year-old Danish driver Kevin Magnussen, who came up through McLaren's junior program and won the Formula Renault 3.5 championship. Magnussen will be the first rookie driver for McLaren since Lewis Hamilton in 2007.
"I'll put it simply: this team is the best. It's been my dream to drive for McLaren ever since I was a small kid," Magnussen said.
Button, the 2009 world champion, said Magnussen displays the "whole package" of a champion driver.
"The speed, the way they learn, marked ability," Button said. "There's a lot a driver has to have to be in a top-flight team and Kevin definitely comes with that."
Maldonado said leaving Williams -- where he had one win in 2012 -- after three years was a tough decision but one the Venezualan feels good about. Maldonado suggested he may be close to a new deal with another team.
"I have a couple of options. We are still working on it and I really hope to have a clear answer soon," Maldonado said.
The driver is just the start of the changes for 2014. Some hope the mechanical changes will bring more parity to a sport that Vettel and Red Bull have dominated, but Vettel predicted the pecking order will look much the same by the end of next season.
"Nobody really knows what's going to happen," Vettel said. "I think you will have the big teams at the front again ... It could be tricky. We'll see."
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