Jules Bianchi (Tech 1 Racing), Robin Frijns (Fortec Motorsports) and Sam Bird (ISR) are battling it out, with Bianchi leading Frijns by five points and Bird a further 19 points back.
Frenchman Bianchi recently took part in free practice at the Korean Grand Prix with Force India and has a stern test in holding off Dutchman Frijns, who has three wins in his rookie season.
If Frijns can emerge on top after Barcelona then he will become the first man to win the 2.0 and 3.5 Series back-to-back, and the first rookie to win the championship since Robert Kubica in 2005.
Bird will likely have to win race one to have any chance to overhauling his two rivals.
Tech 1 and Fortec Motorsports are the two contenders for the team championship.