Participants in Sunday’s Scotiabank Calgary Marathon take note; if you’re passed on the course by a giant dog, you may not be hallucinating.

Andrew Jacobs, a cross country runner from Ponoka, will be competing in this year’s race as Jefferson the Dog, the MyNextRace.com mascot, in the hopes of besting the current Guinness World Record for the Fastest Marathon Dressed as a Mascot.

Sunday’s forecasted high of a sunny 18C is less than ideal for a four hour run in a mascot costume.

“It is warm in there,” said Andrew, a 21-year-old business administration student at Red Deer College. “Hopefully there’s a cold snap June 1 in Calgary. In any case, I’m super excited.”

Sunday's race will be Andrew's fourth marathon but his first race inside a mascot costume. He's been told a Gingerbread man will be racing against him and there are rumors of a racer competing in a sumo suit.

Decreased visibility, the weight of the mascot suit, and reduced air flow are some of the challenges Andrew will face along the 42.2 kilometre course as he attempts to break the current mascot marathon record time of 3:51:50.

While he admits a world record would be amazing, Andrew says his main focus will be enjoying the day.

"My number one goal is to have fun and have a great experience."

Andrew plans to bring a postive spirit to the starting line and he plans to high-five both spectators and his fellow runners along the course.

The rules of the Guinness World Record Attempt prohibit Andrew from removing the mascot head during the race and he'll resort to drinking water through a hole in the base.

The 50th Annual Scotiabank Calgary Marathon starts at 7:00 a.m. at Stampede Park. Andrew and the other marathon runners will race along the banks of the Bow River and through several SW communities before returning to the finish line on the Stampede Grounds.

If his race goes as planned, Jefferson the Dog should cross the finish line prior to 10:52 a.m.

For a list of marathon road closures, visit Roadway Closures & Re-Openings.