If it's significant, I have looked in the past to middle or side the bet, usually in the NBA, but since I want a sure profit, I'll bet half of the matchplay amount as the offset bet, which ensures I'll end up with at least half of the original matchplay amount - for example, betting a matchplay of $500 on the Lakers -11 and taking their opponent +12.5 for $250 - if the Lakers win by 12, I'll win both, if by 11 I'll win the other bet and push the matchplay, otherwise I'll win a little less than $250.
BUT - that's my style, rather the sure thing than the unsure.