mcbee, thank you for your help.
   i am going to lay at over 2.5@2 ,not at 2.02, and waiting, if matched then lay at under 2.5 @1.99 at once.  it will make some little profit. then do it again. 
   the over2.5 price could be between 1.5-2.5.
   also, it will run before turn in play and stop before the match start.