The Semifinals begin in Las Vegas, where the ninjas take on a longer course featuring 10 iconic obstacles from the past. The fastest will advance to the National Finals and compete in head-to-head races.

Qualifying rounds conclude in Las Vegas on the world's most challenging obstacle course. The top 20 athletes of the night advance to the semifinals.

Qualifying rounds continue in Las Vegas on the world's most challenging obstacle course. The top 20 athletes of the night advance to the semifinals.

Qualifying rounds continue in Las Vegas on the world's most challenging obstacle course. The top 20 athletes of the night advance to the semifinals.

Qualifying rounds continue in Las Vegas on the world's most challenging obstacle course. The top 20 athletes of the night will advance to the semifinals.

Qualifiers continue in Las Vegas with a special "How to Train Your Dragon" episode. Dragons Toothless and Stormfly join the ninjas, and the film's star joins Matt and Akbar in the booth.

Qualifying rounds begin in Las Vegas on the world's most challenging obstacle course. The competition returns bigger than ever by bringing back trailblazers, record-setters and fan-favorite competitors from the last 16 seasons.