With just four races remaining, championships are on the line in Pirelli World Challenge as teams head to Sonoma Raceway for the penultimate weekend of the season.

More than 40 cars are expected between the GT, GT-A and GTS classes for the series’ second trip to California this year.

ENTRY LIST: Sonoma

While Johnny O’Connell continues to lead the title race in GT, the gap between the Cadillac driver and CRP Racing’s Mike Skeen is now 82 points entering the doubleheader weekend.

The driver carrying the most momentum, but out of the championship fight, however, is Ryan Dalziel, who is coming off a sweep of the weekend at Mid-Ohio in his EFFORT Racing Porsche 911 GT3 R.

Other contenders this weekend include Andy Pilgrim in the sister Caddy, as well as the No. 61 R. Ferri Motorsport Ferrari 458 Italia GT3 of Anthony Lazzaro, with the team again down to a single-car entry for the second consecutive event.

Dyson Racing Team Bentley, however, has expanded into a two-car operation, with former Le Mans winner Guy Smith joining Butch Leitzinger with Bentley Continental GT3s.

Mike Hedlund, meanwhile, makes his series return, piloting the No. 77 Ferrari for the World Challenge-debuting Scuderia Corsa squad, which along with TRG-AMR is pulling double-duty with fielding entries in Sonoma and the IMSA event at VIR this weekend.

TRG-AMR’s Vantage GT3 also returns with Danish rising star Christina Nielsen, while Alex Lloyd makes his second consecutive start in the No. 12 CRP Racing Corvette, one of the few cars that do not conform to FIA GT3 regulations.

There are no notable entry changes in GT-A, a class which is now led by EFFORT’s Michael Mills, thanks to his double win at Mid-Ohio.

The GTS class sees Kia Racing/Kinetic Motorsports’ Mark Wilkins and Nic Jonsson sit 1-2 in the championship, but have come under attack from defending class champion Lawson Aschenbach in the Blackdog Speed Shop Camaro.

Aschenbach holds an outside chance of the title, but a maximum points weekend at Mid-Ohio helped put him within 164 points of the lead.

Testing gets underway on Thursday, with additional practice on tap for Friday. Qualifying is set for Saturday morning, with Race 1 at 2:35 p.m. PT and Race 2 on Sunday at 4:40 p.m. PT. Both races will be televised live on http://www.world-challengetv.com.