Justin Allgaier on stand-by in Charlotte to drive Kyle Larson's No. 5 car if needed

NASCAR Xfinity Series regular Justin Allgaier will serve as the backup driver for Kyle Larson in this Sunday’s Coca-Cola 600 at Charlotte Motor Speedway.

Allgaier told Bob Pockrass of FOX Sports that he fits into Larson’s seat well and won’t take any laps in practice. He will be present for Saturday’s practice session and be in the debrief meeting in case his services are needed for the 400-lap event Sunday.

Allgaier, who drives the No. 7 Chevrolet for JR Motorsports, sits fifth in the Xfinity Series points standings. The 37-year-old has competed in 81 Cup Series races over the duration of his career. At one point last week, Hendrick Motorsports had Allgaier slated to be the backup driver for Larson in the All-Star Race at North Wilkesboro Speedway, plans which were later nixed. Larson made it in time from Indy 500 qualifying and finished P3 at North Wilkesboro.

Hopefully for Hendrick, Allgaier won’t be needed at Charlotte. However, Larson will certainly be cutting it close as he starts fifth in the 108th Running of the Indy 500 before jetting over to Charlotte for the Coca-Cola 600. Green flag for the Indy 500 will wave at approximately 12:45 p.m. ET, while the Coca-Cola 600 begins at approximately 6 p.m. Larson is attempting to become just the fifth driver to finish the Indy-Charlotte Double and the second to run all 1,100 miles. Tony Stewart is the only driver to do it, finishing sixth in the 2001 Indy 500 before jetting over to Charlotte and finishing third in the Coca-Cola 600.

Weather forecast to impact Kyle Larson’s Indy-Charlotte Double attempt?

Beyond the physical and mental rigors that go into pulling off the Indy-Charlotte Double, there are some factors out of Larson’s control that could hurt his chances. The main one is weather, as the current forecast calls for a 40-80% chance of rain in Indianapolis this weekend, as well as a 30-40% chance of rain in Charlotte.

Larson admitted he’s growing concerned with the prospect of having to pick one race over the other.

“You can have all these plans and backup plans and backup plans for the backup plan,” Larson said Thursday. “But you just can’t really do anything or react until it’s kind of the moment. That’s what’s a little bit stressful.”