The Qantas Wallabies full-back has been in scintillating form since switching from rugby league a year ago - scoring nine tries in 14 Tests.
That included two tries in the opening Test on June 22 that the Lions eventually won 23-21 in a pulsating contest in Brisbane.
And Cuthbert, who also crossed in that opening clash, admits Wales will have stop the marauding 24-year-old if they are to come out on top on Saturday.
"He's the danger man, the man in form and probably one of the best players at the moment in rugby," Cuthbert said.
"He's improving every game and he's the player we've got to mark closely and obviously try and keep him away from the ball as much as possible.
"He's been managing to get the ball a lot and putting Australia on the front foot so if we can stop him then I think we can try and stop Australia.
"They're a quality side and you can never keep them down. It's going to be a tough game at the weekend.
"They're going to look to finish their tour with a win against us so it's going to be a big battle."