Indy Lights Presented by Cooper Tires represents the third and final step on the acclaimed Mazda Road to Indy, a development ladder leading all the way from the grassroots levels of karting and advanced driving schools to the Verizon IndyCar Series and the Indianapolis 500.

What began as the American Racing Series in 1986 is in the midst of a major transition. At the beginning of this year, Andersen Promotions took control of guiding Indy Lights into the future, and this weekend at Sonoma Raceway marks the 169th and final race for the current breed of V8-powered cars which have provided the backbone of the series since 2002 and will be replaced by an exciting new state-of-the-art Dallara IL-15 car/engine package in 2015.

A switch to Cooper tires for this year presented a fresh technical challenge for the teams during this changeover period, and what the fields lack in quantity they certainly make up for in quality. Four different drivers shared the victories during the first half of the 14-race season, and all of them - plus one more regular podium finisher - have retained a chance at the championship crown as the campaign reaches its climax.

Second-year Indy Lights veterans Gabby Chaves and Zach Veach, along with their respective teams, Belardi Auto Racing and Andretti Autosport, have been locked in combat since the beginning of the season.

Colombian-American Chaves, 20, who finished second in Pro Mazda in 2012 and second last year in Indy Lights, was the first to make an impression, taking pole in the opening round on the streets of St. Petersburg in March. Veach, however, grasped the lead at the start and never looked back en route to an accomplished victory. Two weeks later on the streets of Long Beach, the roles were precisely reversed. This time it was 19-year-old Veach who took pole, with a stunning last-lap effort, only for Chaves to snatch the lead at the start and level the score.

Their battle has continued unabated since then, with Veach winning again at Barber Motorsports Park and Chaves taking a thrilling win in the jewel in the series' crown, the Freedom 100 at the Indianapolis Motor Speedway in May - by the narrowest margins, just 0.0050-second!

Veach's teammate, third-generation racer Matthew Brabham, and two more rookie drivers representing Schmidt Peterson Motorsports with Curb-Agajanian, Luiz Razia and Jack Harvey, also have been in the thick of the title-chase.

Born in Florida and raised in Australia, Brabham is well on his way toward emulating the historic feats of his grandfather, Sir Jack, who won three Formula 1 world championships, and father Geoff, whose own accomplishments include four sports car championships in North America and a victory in the 24 Hours of Le Mans. Brabham, 20, won the Cooper Tires USF2000 Championship Powered by Mazda as a rookie in 2012, and last year used his prize – a fully paid MAZDASPEED Driver Development scholarship – to excellent effect by dominating the Pro Mazda Championship Presented by Cooper Tires.

Brabham and Razia, a Brazilian veteran of GP2 in Europe and an ex-Formula 1 test driver, both secured their first Indy Lights wins as part of the Grand Prix of Indianapolis double-header in May, while highly touted Englishman Harvey, a front-runner in last year's GP3 Series, also has been a regular contender.