By Alan Baldwin
LONDON (Reuters) - The clock is ticking for some of Formula One's big name drivers, with world champions and race winners out of contract at the end of the season and a restless young generation eager to take their places.
McLaren's Jenson Button and Ferrari's Kimi Raikkonen, the 2009 and 2007 world champions respectively and both 36, have deals expiring at the end of the year as does Brazilian Felipe Massa (34) at Williams.
Nico Rosberg (30), runner-up to Britain's triple world champion Lewis Hamilton at Mercedes for the past two seasons, also faces contract negotiations having been with the now-dominant team since 2010.
There is no shortage of fast and hungry potential replacements.
"This season, more than others, there are things opening up. It’s no secret. It’s a big prize and that’s why it’s an important season, not only for me," Toro Rosso's 21-year-old Spanish hotshot Carlos Sainz told Reuters.
"It’s my second year and everyone says there’s more pressure in your second year. No. There is the same pressure for me as for every single driver on the grid. It’s an important year for all of us and we are all going to push like hell to get one of those spots."
In Sainz's case, the primary focus is following the familiar path of graduation from Toro Rosso to bigger sister team Red Bull.
But that will require either Australian Daniel Ricciardo or Russian Daniil Kvyat moving elsewhere, as well as him seeing off the challenge of 18-year-old Dutch sensation and team mate Max Verstappen.
"I have no idea what is going to happen. What is true is that for 2017 there are many options, many things opening up," Sainz added.
"What I want to show is first that I can be a top team driver and I want Red Bull to spot that first of anyone. That’s it. If they don’t spot it, or someone else spots it, then it’s not up to me. But I want to show it first for Red Bull."
Raikkonen, who will be 37 in October and is the oldest driver on the grid, was the subject of much speculation last year before he agreed a new one-year deal and will be the key to the impending merry-go-round.
The Finn scored 135 points last year, compared to 266 for team mate Sebastian Vettel who won three races. Many felt he was fortunate to stay, despite being regularly rated as a fan favorite.
Any change at Ferrari -- the sport's oldest, most successful and glamorous team -- is big news and the seat is one every driver dreams of with the Italian team now also Mercedes' closest rivals.
Raikkonen's compatriot Valtteri Bottas at Williams, Ricciardo and Verstappen have all been seen as potential successors while Frenchman Romain Grosjean will be hoping he has put himself in the frame by moving to Ferrari-powered Haas.
"Since I was a kid, since I was five, I wanted to drive for Ferrari. Is it going to happen one day? Is it never going to happen? I have no idea. It would be a dream," Grosjean told Reuters.
Button, who has been in the sport longer than any of the current crop of drivers, considered retirement last year but agreed a one-year extension.
If this is his farewell season, then McLaren already have a ready-made replacement in last year's GP2 champion Stoffel Vandoorne, the Belgian reserve seen as the next big talent waiting to break into the sport.
Any vacancy at Mercedes-powered Williams would have a queue of candidates but Massa wants to stay.
"I don’t feel that," he told Reuters when asked whether this would be his last season.
"I didn’t see yet that I am not quick, that I am not competitive, something that shows me that maybe it is time to stop. Until I see that, I am ready to carry on."
Rosberg, winner of the last three races of 2015 from pole position and 14 in his career, has a crucial year ahead and can take nothing for granted.
Even if major rule changes shake up the pecking order in 2017, almost every driver in the paddock would leap at the chance to replace the German.
Mercedes have a rising star in 21-year-old rookie Pascal Wehrlein, making his debut with tailenders Manor Racing after becoming the youngest champion in the DTM (German Touring Car) championship last year.
There is also Verstappen, who Mercedes tried to sign before Toro Rosso snapped him up at 16 with a guaranteed race seat. If there is a risk of him moving to Ferrari, the champions might want to get in there first.
"I'd probably be looking over my shoulder a little bit if I was Rosberg. At Pascal or Max," 1996 world champion Damon Hill, now a Sky television pundit, told reporters.
(Editing by Ed Osmond)