Source: MotoGP.

The 2015 Moto2 and Moto3 World Championships start this weekend with the Commercial Bank Grand Prix of Qatar.

After the recent weather-affected final preseason test in Jerez, it is hard to predict any favourites for the 2015 Moto2 title as riders prepare to do battle under the lights at the Losail International Circuit in Qatar.

Tito Rabat becomes the first ever Moto2 World Champion since the class began to attempt to defend his title on the Estrella Galicia 0,0 Marc VDS Racing Kalex, with previous champions having decided to move up to the MotoGP class.

Rabat is joined in 2015 by two of the top three Moto3 riders from last season as well as 14 of the top 15 riders in the Moto2™ standings from 2014, with only Maverick Viñales having left the class to join the factory Suzuki Ecstar team in MotoGP.

Speed Up Racing´s Sam Lowes will hope to continue his preseason form during 2015 as he begins his second season in the class, while last years Moto2 runner-up Mika Kallio has made the switch this year to the Italtrans Racing Team.

With serial contenders like Johann Zarco, Luis Salom, Axel Pons, Simone Corsi, Thomas Luthi and Rabat´s new teammate, the 2014 Moto3 World Champion Alex Marquez, also lining up on the grid, it is shaping up to be an incredibly competitive season.

Lone Australian in the field will be Queensland veteran Anthony West, in what is his QMMF Racing Team’s home race to begin this season.

The Commercial Bank Grand Prix of Qatar starts on Thursday with two practice days for the riders, before qualifying on Saturday, with the Moto2 race due to take place at 19:20 local time on Sunday night.

The Moto3 class has always been a platform for the best young riders in the world to showcase their talent and for 2015 this is no different with only four riders competing in the championship over the age of 21.

Frenchman Fabio Quartararo will be the youngest rider to ever to compete in a full season in Moto3, at just 15 years and 343 days, with the organisers having changed the rules this year to allow someone under the age of 16 to take part in a race.

Quartararo was the CEV Repsol Moto3™ Champion from 2014, and has already impressed a number of people with his pace during preseason, having joined the Estrella Galicia 0,0 Team for 2015.

There are a number of new faces that will line up on the grid in 2015, including last years Red Bull Rookies Cup Champion Jorge Martin, who will be joined by Juanfran Guevara and Francesco Bagnaia on the on the Mapfre Mahindra Team.

Quartararo is joined in the Estrella Galicia 0,0 Team by the man who finished runner-up to him last year, Jorge Navarro, while Gabriel Rodrigo will be the first ever Argentinian to compete in Moto3, for the RBA Racing Team.

Maria Herrera will be the second female to compete full-time in the Moto3 class alongside Ana Carrasco, as she becomes teammates with Isaac Viñales in the Husqvarna Factory Laglisse Racing Team.

Efren Vazquez, who took two race wins last year on his way to fourth in the championship, lines up alongside British rider Danny Kent for the Leopard Racing Team, with Scottish rider John McPhee also returning to the the grid with the Saxoprint-RTG Team.

Karel Hanika, Brad Binder and Miguel Oliveira make up an extremely competitive Factory Red Bull KTM Ajo team, while the rider who finished the championship in fifth last year, Romano Fenati, is joined by compatriot Andrea Migno in the Sky Racing Team VR46.

A total of 14 nationalities will be represented on the grid when the lights go out in Qatar, and with less than 0.6s separating the first six across the line last year, it once again promises to be an exciting start to the 2015 Moto3 World Championship.

Remy Gardner enters his first full season of grand prix racing with the CIP Mahindra team, following a number of promising guest appearances last year.

Teams have an extra day of practice at the Losail International Circuit to prepare for the season opener, with things kicking off on Thursday in Qatar ahead of qualifying on Saturday and the Moto3 race scheduled to take place at 6pm local time in Qatar on Sunday.