If you thought just completing a Rubik's Cube was hard enough, these pictures depict the ultimate challenge for addicts of the 80's craze that just won't go away: doing one blindfolded.
The blindfold competition was just one of the events at this year's fourth Rubik's Cube world championship which began in Budapest on Friday.
Blindfold players try to solve the game by memorizing the position of key cubes before covering their eyes.
Rubik's Cube: Hard enough as it is, but blindfolded?
Players, from over 30 countries, can compete in several categories: besides the classic 3x3 Rubik's Cube, which has six sides with six different colours, there will be competitions in 4x4 and 5x5 cubes as well as one-handed, and even feet-only challenges.
Contestants race against the clock to complete the fiendishly difficult cubes
The world record holder for the 3x3 Rubik's Cube event, Frenchman Thibaut Jacquinot, aligned all the colours on his cube in 9.86 seconds at a competition in May of this year.
Too young to remember it the first time around, this young puzzler looks to have it sorted
The frustrating, yet addictive puzzle, was invented in 1974 by engineer Erno Rubik, and sparked a global craze in the early 1980s.
An estimated 9 million cubes were sold last year, taking the all-time total to more than 300 million units.
At this year's Caltech 2007 competition American Rubik's Cube expert Dan Dzoan broke the world record for one-handed cube-solving by completing one in an incredible 17.9 seconds.
Watch the amazing video:-Dan Dzoan broke the world record for one-handed cube-solving