ABC News' David Wright and Rachel Humphries report:

The world's most exclusive club is opening its doors to the average Joe, or in this case, the average Jimmy.

For the first time, the nation's oldest and most prestigious dog competition - the Westminster Dog Show - will allow mixed-breed dogs like Adrienne McLean's Jimmy to compete.

Related: Big change coming to 2014 Westminster Dog Show.

Jimmy, of Richardson, Texas, has no pedigree. In fact, the 8-year-old red-haired terrier mix - named after a long-legged and formerly red-haired uncle of McLean's - is a rescue dog.

"He was dumped at a shelter in Wiley, Texas, at about 7 weeks of age because he had ringworm," said McLean, who drove to New York City this week so Jimmy could compete in this weekend's competition.

Unlike other canine competitors - who look like supermodels, primped and poised and purebed - Jimmy has never had a good hair day.

"If I brushed him, his hair would be kind of wavy and he would just shake himself," McLean said.

But Jimmy has talents - he can jump through hoops and race through tunnels. He's visited more than 25 states doing agility competitions. He was the No. 3 mixed-breed dog in the American Kennel Club in 2012 and won a "Top Dog" prize for placing No. 4 in the 16-inch height at the 2013 Agility Invitational Championships in Orlando, Fla.

He's also a registered therapy dog with Heart of Texas Therapy Dogs. At Kellar's Canine Academy in Saddle Brook, N.J., Jimmy showed off his skills recently.

He is now one of 16 mixed-breed dogs hoping to beat the purebreds in the agility contest - it's the equivalent of an Olympic gold medal.

Jodi Kellar, the owner of the academy, said in the agility competition, trainer and dog performed a sort of "choreographed dance."

"Agility is about building a bond and communication with your dog," Kellar said. "It's a very strategic sport."

McLean said that if a mixed-breed dog wins Westminster, it would mean "any dog can do it and just because your dog doesn't have a pedigree, doesn't mean that it's not a canine athlete."

Phyllis Ensley