It is a question that provokes a lot of head scratching among the athletes who will descend on Leeds this weekend in pursuit of glory in the Columbia Threadneedle World Triathlon Series Leeds men’s race.
The once-all-conquering brothers may not have won any of the last eight World Series races but when the chips are down, and when they are healthy, there is no one better than the West Yorkshire double act.
However, one of the nations hoping to poop the party for the homegrown talent this weekend is the United States.
In Gwen Jorgensen they have the best female triathlete in the world – but on the men’s side they have some catching up to do.
When the question of how to beat the Brownlees was put to Barry Siff, the president of US Triathlon, his answer said everything about the brothers’ standing in the sport.
“The Brownlees are guys I have tremendous respect for, firstly as individuals and people, and secondly as athletes,” he began.
“On any given day they can beat anybody, but on another day there are four or five athletes who are fast; Javier Gomez, Mario Mola, Vincent Luis.
“You have to have the perfect race and they just have to have the slightest nick, and they can be beaten. It’s been shown before.
“But they are the tops – Alistair is the Olympic gold medallist and Jonny has been a world champion. When they’re on form they’re close to unbeatable.”
Superstars on the course, Siff and the triathlon community are also impressed by the off-course demeanour of the famous Leeds brothers.
“Worldwide the Brownlees are massive beacons,” he continued. “I met Alistair at a World Series event in San Diego six years ago and he really put a stamp on the sport.
“He spoke at our USA triathlon hall of fame banquet and he was marvellous.
“The Brownlees are known all over the world, they’re very highly respected and highly regarded. They are great ambassadors for the sport and for Leeds in particular.”
Much is expected of the USA’s Jorgensen this weekend, the two-time defending women’s world champion who is currently fourth in the 2016 rankings.
“Our women’s team is as strong as anyone’s, we could have fielded two teams for Rio and we have a lot of talent on that side of the field,” added Siff of a discipline that is at the vanguard of the movement for equality in global sport.
“What I’m excited about is a tough bike course, a technical one and we’ll see how they do on that. I think we’ll do fine.
“I’d hate to be a guy going up against the Brownlees in their home town.”