Weekly Extreme Sudoku Competition for Dec 23 to Dec 29

Number 640, Extreme
by Crosswords Ltd. January puzzle packs Now Out!. Thanks for supporting our site.
Future Puzzle - will be submitted on the relevant day
1 2 3 4 5 6 7 8 9
A
B
C
D
E
F
G
H
J
6       1 5     4
      3          
3 1     7       8
    8   4 7 1    
  3           4  
    2 1 6   8    
2             5 1
          4      
4     5 3       6