There were little over ten minutes left in Munster's Champions Cup game against Castres on Saturday when Andrew Conway chipped and chased down the wing.
Initially, it looked as thought Conway had slid over for a crucial try. However, after a review, Wayne Barnes called it back for a knock-on.
The knock-on had been partially caused by a tackle from Castres out-half, Benjamín Urdapilleta. The Argentine had slid knees first into the Munster winger.
That is a style of tackle with which Brian O'Driscoll took issue on BT Sport.
"It is clear that Conway does knock the ball on but look at that for leading knees," said O'Driscoll.
It's actually something that needs to be stamped out of the game. I'm disappointed to see that referees are letting that go.
I'm really disappointed because Conway missed the summer tour of Australia because of a knee drop of a similar kind. He's not going for that with his feet.
It's not football, you can't have a slide tackle. He's not even trying to go for it with his arms.
I don't think it's a penalty try because I don't think you can guarantee that Conway is going to pick that up and score it.
I do think it's absolutely a yellow card and EPCR and World Rugby need to stamp down on that. It's a blight on the game.
O'Driscoll also said that Castres replacement hooker, Marc-Antoine Rallier, could easily have been shown a red card rather than a yellow for a dangerous tackle on Peter O'Mahony during the same phase of play.
"It's not football, you can't have a slide tackle!"
"World Rugby need to stamp down on that, it's a blight on the game."
In a game with many moments of questionable play...
Brian O'Driscoll feels Munster were very hard done regarding this Andrew Conway disallowed try. pic.twitter.com/hw2emTpPP3
— Rugby on BT Sport (@btsportrugby) December 16, 2018