The 144th Annual Kentucky Derby is upon us, which means once again ... some of your favorite celebs are there trying to one-up each other in the style department.

Johnny Knoxville, Von Miller, Tina Knowles, Anthony Anderson, Laila Ali, Joey Fatone, Aaron Rodgers and his Packers teammates and many more have gathered at the Churchill Downs racetrack in Louisville for the annual running of the race, and as you can see ... there's no shortage of fancy suits and dresses, pastel colors and extravagant hats.

Tara Lipinski and Johnny Weir shared their fashion expertise during pre-race festivities once again, too.

The Derby is the first of 3 races that makes up horse racing's triple crown, and it's definitely tops in bringing out the stars.

This year's favorite is Justify at 3-1 odds, followed by My Boy Jack at 5-1 and both Audible and Mendelssohn at 6-1. We broke the story ... huge underdog Solomini might be a horse to keep an eye on too.

And they're off! (around 3:45 PM PT)