By Aaron Burns

No one knew what to expect when Tony Stewart broke into the NASCAR Sprint Cup Series in 1999.

As a rookie with Joe Gibbs Racing, Stewart was tasked with the job of chasing a Winston Cup title while driving an orange No. 20 Home Depot Pontiac.

The fact that Stewart began his career driving a Pontiac in the Winston Cup Series accurately dates just how long he’s been a part of NASCAR’s highest level of competition.

But he’s been more than just a part of it. He’s played a lead role for the better part of two decades.

It was reported on Sunday that Stewart will retire from Cup competition at the end of the 2016 season, bringing an end to a career that has included 48 wins and three series championships.

He had what was, at the time, the best rookie season in Cup history: Three wins, 12 top-fives, 21 top-10s and a fourth-place finish in points.

Stewart followed that up with titles in 2002, ’05 and ’11 – in the closest Chase for the Sprint Cup battle ever – to cement his legacy as one of NASCAR’s greatest drivers.

As a team owner, he won the title behind the wheel in 2011. He won it again with driver Kevin Harvick last year.

But Stewart’s retirement shouldn’t come as a huge surprise.

He’s got just two top-10 finishes in 28 races this season, he hasn’t won since June 2013 and he ranks 26th in points. Stewart has had as tumultuous a last two years as any driver ever, and the wear and tear on his body and his mind has weighed heavily on him.

Like the feeling we’ll get when Jeff Gordon moves into the FOX broadcast booth next year, it’ll be strange to see a race without Tony Stewart in it.

He’s been a link between the Gordon and Dale Earnhardt Sr. eras and the Jimmie Johnson era. He’s also been an influential part of the sport.

But he’s never won a Daytona 500, and next year is his last chance.

It’ll be fun to see him go for it.