Mano a womano

Slogging slowly through Game Change by John Heilemann and Mark Halperin, the inside story of the 2008 presidential campaign, I came upon this statement describing the aftermath of the South Carolina primary, which drove John Edwards out of the race:

". . . what had been a de facto two-horse race since Iowa was now officially mano a womano."

The authors probably know better and are just having fun with words, but the phrase mano a mano creates confusion for some readers. It means "hand to hand," but some people seem to think it means "man to man," hence the mano a womano pun.