An accountant from the Czech Republic has beaten players from 21 other countries to win the inaugural world Sudoku championships.
The winner saw off challenges from 84 other finalists
Jana Tylova, 31, saw off challenges from two US competitors - a Harvard University graduate student and a software engineer - to take the honour.
After a preliminary qualifying round, 85 puzzle-solvers took part in the two-day event in Lucca, Italy.
Competitors tackled the classic 9x9 Sudoku grid and a range of variations.
These included Diagonal Sudoku, Irregular Sudoku, Sum Sudoku, Toroidal Sudoku and Odd/Even Sudoku.
Ms Tylova was regarded as a somewhat surprising winner after only lying in ninth place at the end of the first round.
"I find it very difficult to give advice at all, but I can advise people to practise every day and to follow websites where there are a lot of games available," she said.
Ms Tylova was presented with her winner's trophy by retired Hong Kong criminal court judge Wayne Gould, who has helped popularise the pencil and paper number game of logic.
His syndicated Sudoku games now appear in more than 400 newspapers around the world.
The competition also attracted entrants from countries including Austria, France, Germany, Poland, India, Italy, Japan, Venezuela, the Philippines, Turkey and the UK.
HOW TO PLAY SUDOKU
Grid: Classic Sudoku is a grid divided into nine 3x3 boxes
Aim: Fill grid so that every row, column and 3x3 box contains the digits from 1 to 9, without repeating
Skills: Reasoning and logic. No arithmetic needed
But organisers have said they had still not yet decided if the world championships will become a regular event.
Thomas Snyder, 26, who was leading the competition until the final round, came second, while Wei-Ha Huang, 30, who works for internet search engine firm Google in California, took third place.
Women made up about one third of the competitors but Ms Tylova was the only one to finish in the top 18.
"There is no difference between men and women and I tried to prove that even in logic, men and women are on the same level," she said.
The game's origins probably lie in a puzzle called Latin Squares, devised by the Swiss mathematician Leonhard Euler in 1783.
It surfaced in the 1970s in a US puzzle magazine, with its squares patterned in the nine-by-nine shape, and caught on in Japan in the mid-1980s.