Reigning 450MX national champion Jett Lawrence has been ruled out of his AMA Pro Motocross Championship title defense after sustaining a thumb injury while practicing at his base in Florida on Tuesday.

Lawrence – who completed a 22-0 perfect season as a rookie on his way to the title last year – will undergo surgery on Thursday in Colorado.

X-ray and MRI scans this week revealed that the 20-year-old has a torn ulnar collateral ligament (UCL), but is aiming to return in time for September’s SuperMotocross World Championship (SMX) post-season. He was also named as part of Australia’s Motocross of Nations (MXoN) team today, which is scheduled for October.

“It’s obviously a bummer, but it’s part of our sport,” Lawrence commented. “It was honestly a pretty small crash, but it is what it is. I’ve been pretty lucky with injuries in my career so far, so I guess it’s just my turn. I was happy with the progress we’ve made in the championship since my setback at Hangtown and I was excited to try and keep my championship.

“That obviously won’t happen now, but I have a good team around me and will focus on getting healthy again and coming back at 100 percent. I look forward to cheering on Hunter and doing whatever I can to help him the rest of the series.”

Team Honda HRC manager Lars Lindstorm added: “We’re fully behind Jett and will support him through his recovery. It’s pretty crazy that three of the championship’s top riders have now been sidelined with the same injury [Lawrence, Eli Tomac, and Cooper Webb], especially one that’s typically pretty rare.

“Of course, it’s disappointing, but even though Jett has won the last seven championships he’s competed in, he’s still so young and has a lot of success ahead of him. Physically he’s a freak of nature and a specimen, so to keep it that way, allowing him to heal to 100 percent is the goal.

“With Hunter currently leading the points chase, I like our chances of keeping the AMA Pro Motocross 450 Championship with Honda, and we look forward to working on that this weekend at RedBud. In the meantime, everyone on the team and at Honda sends their love Jett’s way – we’ll miss having him on the line!”

Lawrence has won the past three rounds of the season at Thunder Valley, High Point, and Southwick, despite still encountering pain in his shoulder in recent rounds. As a result of crashing out of the opening moto at Hangtown, he sits third in the standings – three points outside of elder brother and teammate, Hunter Lawrence.