Sean O'Brien and Peter O'Mahony boast the qualities to rattle the All Blacks for the British and Irish Lions, according to James Haskell.
Haskell will face the Chiefs in Hamilton on Tuesday as the Lions' three-Test series with New Zealand hurtles into view.
The tourists will take on the All Blacks for the first time in Auckland on Saturday, with Haskell and the rest of the midweek team still busting a gut to force their way into boss Warren Gatland's Test plans.
But the Wasps man, running the rule over the Lions' back-row stocks, talked up their impressive options.
"Taulupe Faletau has been fantastic, Sean O'Brien has been excellent and Ross Moriarty showed in the first game why he's on the tour," said Haskell.
"And Pete led by example the other night. They are all fantastic and offer a big point of difference."
"It's those two I'd have to put my hand up and say I'd be concerned about."
Munster captain O'Mahony will be favourite to captain the Lions against New Zealand should tour skipper Sam Warburton not start the opening Test.
Warburton has been battling an ankle problem, but the Lions bosses now expect him to be fully ready to take on back-to-back world champions New Zealand.
He could yet slot in at blindside flanker in Saturday's Eden Park opener, which would mean O'Mahony dropping to the bench and O'Brien continuing at openside.
O'Mahony and O'Brien terrorised New Zealand in a stunning 20-minute burst when Ireland lost a thriller 24-22 in Dublin in 2013.
The All Blacks were stunned by the Irish back-row's ferocity that day, and the Lions will be hoping to capitalise on that in the fast-approaching Test series.
"It's probably Sean O'Brien or Peter O'Mahony that I'd be slightly concerned about - not necessarily because of the physical thing, but because they are completely mental," joked Haskell.
"So I'd be worried if I took them on what might happen to me in the car park later on!
"I've been sharing a room with Sean all tour and we've bonded, to say the least.
"But it's those two I'd have to put my hand up and say I'd be concerned about."
Haskell knows he is now a long shot to feature in the first Test. The issue did not even need to be raised when the Wasps flanker met the press on Monday.
But the 32-year-old did highlight the importance of the Lions' midweek men hitting back to winning ways, after the 22-16 Blues loss and the 23-22 Highlanders defeat.
"If we look at the Blues and Highlanders games: did we deliver? Did we have control? The answer is probably not - but did we learn from it? Yes," said Haskell.
"The Chiefs are going to run it from everywhere, take their quick throws - but if we can play our game with intensity and energy then the result will go our way."