EVEN the 'Terminator' force that is Cardiff Blues number eight Xavier Rush was hard-pressed to deal with the violent discharge of raw energy, power and aggression of Leinster's Seán O'Brien in the PRO12 League last Friday night.
You see 'Seanie,' as he is known to his fellow players, is in the hurting business. All the politically correct jargon, like 'relishing contact' and 'dominating the tackle,' are just nice words for working against the pain barrier.
To thrive at the highest level, you have to give and take punishment. You hurt people and they hurt you. It is those who can deal with the pain and move beyond this barrier that profit.
Leinster back rower O'Brien is one of those demons with a super-human threshold for pain and a super-charged appetite to dish it out wherever and whenever necessary. He relishes contact.
"There is a conveyor belt of back rowers being bred," he said, at Leinster's press gathering this week.
For sure, the hard edge required for this job specification is bred into men, not beaten into them. You are simply made hard enough or not.
O'Brien will look to use his explosive speed and power to unsettle Bath's big-name signing Stephen Donald at The Recreation Ground in the Heineken Cup on Sunday.
"I wouldn't say he is any more of a target than anyone else they have. He had a rest last week along with another few of their key players," said O'Brien.
"He will be fresh and he will want to make a statement in the Heineken Cup this year. He is obviously a great player and we will have to keep an eye on him".
Whatever about Donald, Bath are not the all-powerful force they once were in the 1980s when legendary coach Jack Rowell oversaw their rise to become the second European champions in 1998.
Sadly, they have learned the hard way that if you stand still, you get run over by someone like Seanie O'Brien. Ian McGeechan's men have lost their last three in the Aviva Premiership to be moored in third last.
"We've seen before not to underestimate teams like that, who haven't been playing well. It will be a massive physical challenge for us," stressed O'Brien.
"We are expecting them to come out all guns blazing, especially in front of their home crowd. They'll be hurting I suppose. I am sure they won't bring in the form they have been showing in the last few weeks.
"They are going to target this game to get back to winning ways. It is as simple as that. They are going to come out and try and bash us up".
The quick-fire back-to-back rounds can make and break the ambitions of those who are competing for a place in the last eight. The holders, Leinster, can take complete control of Pool Three and end Bath's interest in the competition if they get their way.
"It is the same as always. We know how important back-to-back games are in this competition. We will look no further than this weekend until the match is over," said O'Brien.
"If anything it is a tougher task to go away first. There are no easy games. There never have been. It is going to be a battle. We know what is expected of us and what type of game it will be.
"We want to play at a tempo and get into the way we like to play the game. They will want to play their game. We will have to start fast. It is everything in these games -- not to give them momentum."
If you want momentum, here he comes.