Defending champions Mercedes are one of just two teams with an unchanged driver roster this season. Five-time champ Lewis Hamilton and his Finnish wingman Valtteri Bottas will try to maintain the team's perfect record in the turbo-hybrid engine era. Ever since the major engine overhaul of 2014, Mercedes have won everything in sight. Is it time for a change?

Ferrari's 2019 challenger has been reliable and consistently quick in preseason testing, prompting the inevitable headlines asking if this might be their year. But, if so, whose year? Team leader Sebastian Vettel will face a new challenge from within this season, the highly fancied 21-year-old Charles Leclerc from Monaco. Leclerc has moved up from Sauber, replacing Kimi Raikkonen.

A Mercedes in hot pursuit of a Ferrari. Lap times in testing can be misleading, at best, but two weeks in Spain suggest this might be a common image in 2019. Being from Monaco, Charles Leclerc technically can't break an improbable French F1 drought. The last driver from the birthplace of motor sport to win an F1 race was Olivier Panis at Monaco in 1996, 17 months before Leclerc was born.

But Leclerc isn't the sole Francophone hope of 2019. Red Bull have also promoted Pierre Gasly (r.) from Toro Rosso. Gasly, at 23, is older than his prodigious 21-year-old teammate Max Verstappen. Now powered by Honda engines, after burning every last bridge with Renault, Red Bull will be hoping for reliability and straight-line speed to match their nimble car's performance in the corners.

Red Bull's junior outlet has the same Honda engines but older drivers than its sister team this season. Thai driver Alexander Albon, 22, makes his F1 debut after finishing third in last year's F2 championship. He's racing with Daniil Kvyat, a Russian 24-year-old who drove for Toro Rosso and then Red Bull in the past, before being ousted to make space for Max Verstappen.

Daniel Ricciardo surprised Red Bull last season when he announced he'd be leaving the team. That means some serious intra-team competition for German veteran Nico Hülkenberg. Hülkenberg's nickname of The Hulk requires little explanation, while Ricciardo likes to think of himself as the honey badger — one of nature's fiercest smaller mammals — so don't be surprised if sparks fly.

Like Mercedes, Haas F1 have opted to hold station in 2019. Their engine deal and technical partnership with Ferrari stands. And behind the wheel, Romain Grosjean and Kevin Magnussen (pictured) will team up again, seeking more midfield overachievement. The rest of the grid might not be so chuffed about this, considering the complaints about Magnussen's aggression in the past few seasons.

For the second time in the Swiss team's history, Sauber has given up its name to please its partners. In the past, it was BMW, but now the Alfa Romeo brand is returning to the F1 grid. Alfa, part of the Fiat family that includes Ferrari, is expanding on its 2018 sponsorship presence. Kimi Raikkonen returns to the team where his career began in 2001, driving with Italy's Antonio Giovanazzi.

You may recognize this hot pink bodywork as the trademark of Force India in recent seasons. And you'd be right. But Force India needed a midseason rescue in 2018 as lawsuits and insolvency proceedings caught up with Indian businessman and politician Vijay Mallya. A Canadian consortium came to the rescue, and the team's been renamed Racing Point F1 for 2019.

One change seemed inevitable at Racing Point once it emerged that Lance Stroll's father, Lawrence Stroll, was spearheading the takeover of the team. Stroll joins after some difficult seasons in the struggling Williams car. Judging by 2018's performance, he may have a much better car driving with Sergio Perez this season. Although losing 2018 prize money (due to the bankruptcy) may hurt the team.

McLaren have brought in Spaniard Carlos Sainz from their engine suppliers Renault to lead the team in 2019. Teenage British talent Lando Norris, runner-up in the F2 feeder series last season, will debut in the big leagues. The struggling giants will hope to move back towards the pointy end of the grid, territory the Woking team has never occupied since the 2014 changes to the engine regulations.

The grid's lacking a double champion in 2019. That said, Fernando Alonso (r.) couldn't keep away from testing in his native Spain. McLaren unveiled Alonso on week 2 as an ambassador to the team, saying he would test the MCL34 car later in 2019. Alonso will be at the Indy 500 and racing for Toyota in the World Endurance Championship this season, but maybe his days in F1 aren't yet numbered?

One veteran departs, while another returns. Polish fan favorite Robert Kubica was seen as a serious rival to the likes of Hamilton, Alonso and Vettel in 2011 when a rally crash almost cost him his life and did cost him part of his right forearm. Without that crash, he would have been driving a Ferrari in 2012. Eight years on, he'll be rejoining the grid far nearer the back, at Williams.

The bad news for Kubica, and British rookie George Russell, is that the team looked in dire straits in preseason. Drivers and mechanics twiddled their thumbs for most of the first week of testing, waiting for a working FW42 car to arrive in Spain. Using these scaffold-like "aero rakes" as late as the penultimate day of testing is a surefire sign they're struggling with aerodynamic performance.