Yahoo! and Microsoft hope that by joining forces, they can tilt the balance of power in Internet search away from Google. First, however, Yahoo and Microsoft’ve to convince regulators that their plan won’t hurt online advertisers and consumers. As the U.S. Justice Department reviews the proposed partnership, approval figures to hinge on this question: Will the online ad market be healthier if Google’s dominance is challenged by a single, more muscular rival instead of two scrawnier foes? The Microsoft-Yahoo alliance may stand a better chance of winning antitrust approval than the Google-Yahoo pact because it would combine the second and third players in the search market instead of the top two, said Melissa Maxman, head of the antitrust practice group at Baker & Hostetler LLP. In fact, a combination of Microsoft and Yahoo would still lag far behind Google. Google handled 64.7 percent of all U.S. Web searches in July, while Yahoo processed 19.3 percent and Microsoft 8.9 percent, according to comScore Inc, reports AP.