A momentary lapse in concentration is all it takes for a goalkeeper to be punished by the likes of Luis Suarez and Daniel Sturridge, according to John Achterberg.
Liverpool's goalkeeping coach, who made over 250 appearances for Tranmere during an 11-year spell, is glad he was never tasked with keeping the Reds' deadly duo at bay.
He watches them at close-quarters on a daily basis at Melwood - and has offered an insight into why they strike fear into the heart of opposition stoppers.
Achterberg told Liverpoolfc.com: "It's a different level to the one I played at in my playing career, but they have so much quality it's difficult for any defence and any goalkeeper to deal with.
"The best aspect of their partnership is their ability, in terms of technical movement and vision.
"They can do the unexpected things - quick turning, shooting or seeing the goalkeeper make a little movement and use it to put the ball the other way.
"They'll catch 'keepers off balance at times as well and use it to their advantage. Any goalkeeper is going to be struggling to make saves."
As the likes of Sturridge and Suarez depart on international duty this week, Achterberg will be at Melwood, working with the club's younger 'keepers.
He's more than happy to offer pointers and help guide those who make the step up to train at the first-team's base - and the 42-year-old explained how he continues to keep tabs on the youngsters as the season progresses.
"When the young players come up here in the international break, you want to help them," said Achterberg.
"I know them all because I always get the clips of every 'keeper from the U15s upwards and I'll watch if I can during mid-week.
"Sometimes of a Sunday, if we're off, I'll be watching their games. This is all so that I know all the goalkeepers.
"I've worked with a lot of them in the past as well, so I know them and I know what they need to work on and I try and help them to improve in their game."