THE BRAIN BUSTING SUDOKU

Sudoku is a logic-based, combinatorial number-placement puzzle. The objective of the Brain Busting Sudoku is to fill each 9×9 grid with digits so that each column, each row, and each of the nine 3×3 subgrids that compose the grid (also called "boxes", "blocks", or "regions") contain all of the digits from 1 to 9. 

Baron Bad Guy has provided a partially completed grid, which for this well-posed puzzle has but a single solution.
Baron Bad Guy's Brain Busting Sudoku puzzle