Sudoku Players' Forum (clone)

_ 5 _ _ _ 1 4 _ _
2 _ 3 _ _ _ 7 _ _
_ 7 _ 3 _ _ 1 8 2

_ _ 4 _ 5 _ _ _ 7
_ _ _ 1 _ 3 _ _ _
8 _ _ _ 2 _ 6 _ _

1 8 5 _ _ 6 _ 9 _
_ _ 2 _ _ _ 8 _ 3
_ _ 6 4 _ _ _ 7 _

Have a close look at the possible values for r3c3.