Last year it was $1 million, and this year it’s a private island.

Adidas has upped the ante when it comes to the prize it’s willing to give if a participant in this year’s NFL combine breaks Chris Johnson’s record of 4.24 seconds in the 40-yard dash. And while most will admit that it’s no easy task, there are plenty of speedsters participating in this year’s event who will have a shot at earning the incredible prize.

We break down five players we think have the best chance to break Johnson’s record.

The former five-star athlete committed to USC on National Signing Day in 2014. He went on to star on both sides of the ball for the Trojans and capped off his career by winning the Thorpe Award in 2016. Most view Jackson as a first-round pick and his speed has a lot to do with it. Jackson was also a member of the Trojans' track team, and his career highlights include placing second in the Pac-12 in the 100 meters in 2016. He’s also an accomplished long jumper. Many believe he has the best shot of anybody at getting close to Johnson’s mark.

The former four-star Orlando product committed to Florida State over Florida back in the 2013 class, and the speedster went on to have a very productive career in Tallahassee. Because of his size some view him as a fringe NFL Draft prospect, but with his elite speed and a good showing at the combine he could be a late-round pick. Whitfield had more than 1,000 career receiving yards with the Seminoles and was also one of nation’s best kickoff returners. In high school he was the Florida state champion in both the 100 and 200 meters.

As a three-star prospect coming out of high school in South Florida, Moreau was passed over by the “Big Three” in the Sunshine State. He ended up committing to UCLA just a few weeks before National Signing Day and it turned out to be a good decision. He moved from running back to cornerback in college and improved as his career moved along. Some draft experts see him as a mid-round pick, but UCLA coaches have talked up his speed in the past. He’s been timed at sub-4.4 but will have to improve on that mark to get close to Johnson’s record.

A three-star prospect out of Washington, Rector committed to the Cardinal on National Signing Day in 2012. Some might be surprised to see his name on this list, but the Stanford speedster is one of the nation’s fastest players. He’s been timed in the 4.3 range and was an accomplished track athlete in high school, competing in the 100, 200 and 4x100 meter relay. Thought by many to be a mid- to late-round pick, he could solidify his stock by clocking an impressive time.

A former two-star, Williams committed to the Utes out of ASA junior college in New York just before National Signing Day in 2015. His career in Utah saw its ups and downs, including when he “retired” from the game early in the 2016 season. After injuries he was asked to re-join the team and he went on to have a massive year, finishing with 1,407 yards while playing in just nine games. Williams was a high school track star specializing in the 100 and 200 meters and has the potential to be the fastest running back at the combine.