Please Explain this line?

<TABLE class=module borderColor=#111111 cellSpacing=0 cellPadding=0 width=800 border=0 rgfloat="440,600"><TBODY><TR style="HEIGHT: 28px" vAlign=bottom bgColor=#f6f6f6><TD noWrap></TD><TD noWrap>325 </TD><TD noWrap>V.Williams Wins 1st Set</TD><TD noWrap></TD><TD noWrap>+100 </TD><TD noWrap></TD><TD noWrap></TD><TD noWrap></TD></TR><TR style="HEIGHT: 28px" vAlign=top bgColor=#f6f6f6><TD noWrap></TD><TD noWrap>326</TD><TD noWrap>S.Williams Wins 1st Set</TD><TD noWrap></TD><TD noWrap>-120 </TD><TD noWrap></TD><TD noWrap></TD><TD noWrap></TD></TR><TR style="HEIGHT: 28px" vAlign=bottom bgColor=#f6f6f6><TD noWrap></TD><TD noWrap>325 </TD><TD noWrap>V.Williams 1st Set Games Won</TD><TD noWrap>+½ -135 </TD><TD noWrap></TD><TD noWrap></TD><TD noWrap></TD><TD noWrap></TD></TR><TR style="HEIGHT: 28px" vAlign=top bgColor=#f6f6f6><TD noWrap></TD><TD noWrap>326</TD><TD noWrap>S.Williams 1st Set Games Won</TD><TD noWrap>-½ -105 </TD></TR></TBODY></TABLE>

If you are betting Serena to Win the 1st set, why wouldn't you just bet her -1/2 for the 1st set, less juice and even if she wins 7-6, you still win.

Am I missing something about the wager?

no you are not missing anything. those 5 dimes lines move around a bit and you can find some good deals looking at those options and choices close.

If Serena wins it 7-6 in a tiebreaker, maybe the Serena -0.5 games will be graded a loser (since they might not consider winning the tiebreaker as winning a game), while Serena winning the first set would be graded a winner. That might be the reason for the price discrepancy.

Same way sometimes you'll get to see an NBA team at a pk, yet the line is like -120(5)....The line was perhaps at -1.5, went to a pk, line mover moves the spread to 0 but fails to move the ML to -110...