The Challenge Champions kicked off the newest season — Invasion — by suffering a stunning defeat.

On this week’s episode, the first that pit eight returning Champions against 12 winless Underdogs, the show’s team of Davids stood up to its Goliaths and thrived. As part of “Knockout,” contestants — in separate men’s and women’s heats — had to collect a ball that had been launched off of a catapult and get it into their team’s respective bucket…all while fending off the other team’s players.

Though the Champions kicked off the game with four fewer players, most still insisted their team had the game in the bag. But as soon as Ashley scored the very first point of the game and gave the Underdogs a lead, it was clear that the champs weren’t exactly sitting pretty.

“These underdogs are looking pretty hungry,” CT said. “I don’t think it’s gonna be as easy as the champs think.”

And, after a pair of unanswered points from Nicole and Ashley, the Underdog women handily defeated the Champions in the game’s first half.

“These vets came into this game thinking that they were going to completely dominate, and we’re gonna put up a good fight,” Amanda said.

Cara Maria couldn’t argue.

“We show up as these hot-shot Champions…and then they win. It basically just pops the air right out of my balloon,” she said.

Bananas, who watched the women’s heat from the sidelines, echoed the sentiment as he prepared for the men’s heat.

“Our girls are just making these Underdog girls look way better than they should,” he said.

Still, as he’d find out minutes later, the Underdog guys were just as eager to fight.

Immediately after Round Two began, the Underdogs took control, and Dario scored the first point easily. The champs’ guys explained that they had a particularly tough time dealing with the deficit of players and couldn’t seem to shake The Underdogs.

Cory, who quickly scored a follow-up bucket, made sure the Champions had no wiggle room.

“We’re the champs and we’re getting our ass whooped,” Darrell lamented. “I don’t care if they’ve got more people, we need to put the damn points on the board.”

And while the Champions’ men did just that — Darrell sunk a quick bucket and Bananas followed up with a game-tying point — it wasn’t enough. After a final point scored by Tony, the game was decided, and the Underdogs officially claimed the first victory of the game’s post-Shelter leg.

“This is crazy -- we just beat Challenge legends,” he said. “This is the best feeling.”

Unfortunately for the Champions, it was the worst, and the game’s reigning victors got a pretty clear signal that the game might not be as easy to win as they imagined it might have been.

What do you think: Will the Underdogs prove to be bigger threats to the Champions than the winners first expected they would? Or did the Underdogs only prevail because they had more players, and will the Champions fare better at the next mission? Share your thoughts, and be sure to tune in to a new Challenge: Invasion of the Champions tonight at 9/8c!