MANILA -- Sarah Cua, 14, thought she would end up a runner-up in a numbers game against competitors from five other countries when somebody finished the last puzzle ahead of her.

But when the winners were called, the Filipino teen from Pangasinan was declared champion of a Sudoku tournament in the Asia-Pacific in Singapore on Saturday.

The number-placement puzzle challenges players to fill empty blocks in nine-by-nine squares with the correct digits so that each row, column and quadrant will have digits one to nine without any repetition.

?The last puzzle was so difficult, it was an expert-level puzzle and the time limit was 50 minutes. I passed [my finished puzzle before the limit]. Somebody finished ahead of me but, unfortunately, she made a mistake,? Cua said at the airport on Sunday.

She said she was too shocked. ?It was really unexpected,? she told reporters upon arriving in Manila Sunday afternoon.

Cua, a second-year high school student at the Pangasinan Universal Institute, bested 50 other contestants from China, Malaysia, Thailand, India, host country Singapore and the Philippines in the Sudoku open that accepted Asian players of all ages.

Besting five other Filipino players, Cua took the champion?s trophy and 10,000 Singapore dollars (more than P330,000), finishing the final puzzle in 15 minutes with all digit entries correct.

She also took home a hamper of products from brain vitamin BRAND?s, organizer and host of the Sudoku challenge.

?When it was down to 5, the Malaysian contestant finished first so we felt we had a second-placer. But when all contestants finished the puzzle, the one who submitted first was declared fifth-placer because she was incorrect. So we had a champion,? said Cua?s coach, Sid Aguilar of the Philippines? Mathematics Trainers? Guild (MTG).

The championship came two years since Cua solved her first Sudoku puzzle, which she encountered through training with the MTG.

A consistent topnotcher in her school, Cua was among math whiz kids that the MTG, an organization of Filipino math teachers, took under its wings and trained for mathematics competitions in the Philippines and abroad.

Competing against a crop that included fellow teeners and professionals, Cua showed a fighting chance early in the competition, only her second math competition abroad for which she had spent several weeks training.

She placed 6th among 15 players that pushed on to the second round after the easy-level challenge. In the next rounds, she consistently placed first.

?She became the darling of the press during the marathon competition because she was consistently making first place so all cameras were on her. She was already leading so she began feeling nervous,? Aguilar said.

As cameras clicked away into the final round, Cua zeroed in on her game as it required intense focus and analysis. It was just her against a game sheet with 22 digits as the only clues in an 81-block puzzle.

?I calmed down and I just didn't mind [the people] around me. I just concentrated [on the puzzle],? she told the Philippine Daily Inquirer.

An intense math trainee since third grade, Cua is bound for Singapore again this week for the International Mathematics Competition on July 18.

Responding to a joke on why she didn?t just stay in the city-state until her next contest, Cua said with a shy chuckle: ?Because I have to go to class.?