Ospreys lock James Fender received a red card on the stroke of half-time for a dangerous croc roll in a ferocious Welsh derby against Cardiff.

With the Ospreys trailing 5-3 after 38 minutes, television match official Tom Spurrier alerted referee Ben Breakspear to a dangerous croc roll by Fender.

The 23-year-old attempted to clear out Cardiff openside Dan Thomas at a ruck but put all his weight down on the exposed lower limb which could have resulted in a serious injury.

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Breakspear deemed the action as highly dangerous and decided to give Fender his marching orders. "It's a tough croc roll," said former Cardiff and Wales openside Ellis Jenkins who was working as a pundit for BBC's ScrumV.

"It's something we don't want to see. We've seen a lot of injuries from that type of movement.

"It's a tough one for James Fender. He hasn't meant to do it but in the referee's framework it is clearly a red card."

Former Wales wing Cuthbert believes World Rugby are right to clamp down on croc rolls.

"They are really big on this this year," said Cuthbert on ScrumV. "There's been so many horrific injuries and there's been no repercussions for them.

"They've really clamped down have World Rugby. He's fallen over with his weight and grabbed him as well. It looks quite nasty."

Former Wales backrower Jenkins was quick to stress Thomas was lucky not to sustain a serious injury.

"Dan Thomas is very lucky there that he managed to get away and managed to get his foot off the floor because if your studs get stuck in the floor and you get some weight on the side... if somebody else hits you from the other side you're in danger," said Jenkins.

"He's a lucky boy."