Last year Carl Edwards finished the season in fourth in NASCAR's Sprint Cup standings and second in the Nationwide Series.
Don't expect that to happen again. Drivers in NASCAR's three series -- Sprint Cup, Nationwide and Trucks -- will not be allowed to accrue points in more than one series for the 2011 season.
The requirement first was reported by NASCAR.com, which spoke to driver Kenny Wallace about the application he filled out last weekend.
Rumors of several changes to NASCAR have swirled ahead of the sport's "competition update" slated for Jan. 21, but it appears the series designation is one that will go into effect this season.
"The brand-new license forms that are out, there's a box and in it, it states that you have to mark -- put an X -- what championship you're running for," driver Wallace told NASCAR.com.
"A driver will only be permitted to earn driver championship points in one of the following three series: NASCAR Sprint Cup, NASCAR Nationwide or NASCAR Camping World Truck Series," Wallace said, reading his application. "Please select the series in which you would like to accumulate driver championship points. Choose one."
NASCAR has declined to discuss the policy change because officials plan to make all their competition announcements over the next few weeks.
Wallace confirmed the requirement in a post on his Twitter page.
Designed to be a feeder series where young talent can develop, the Nationwide Series is instead dominated by NASCAR's Cup stars. The last five champions were all full-time Cup drivers, and Justin Allgaier was the only non-Cup driver to win one of last season's 35 Nationwide races.
Keselowski and Edwards were the only two drivers who had planned to run the full schedule in both series.
NASCAR likely will not limit the amount of Nationwide and Truck Series races that Cup drivers can enter. Doing so could be a deterrent to many fans, some of whom only get to see NASCAR's stars race live in those lower-tier series.
Information from The Associated Press contributed to this report.