Microsoft's proposed search and advertising partnership with Yahoo stands a better chance of winning regulatory approval than Yahoo's previously proposed deal with Google did, but it's not a slam dunk. That's the takeaway from two articles this morning quoting antitrust experts evaluating the prospects for the deal.

The Associated Press quotes Melissa Maxman, head of the antitrust practice group at Baker & Hostetler LLP, saying that the deal probably won't raise nearly the same level of concern because the companies' combined market share will still lag Google by a considerable amount. At the same time, she notes that regulators are tasked with keeping the market from becoming too concentrated.

Antitrust attorney Matthew Cantor tells the AP that the deal will face hurdles: "If the traditional antitrust doctrines are followed, it is going to be hard for the authorities not to challenge this deal, unless some conditions are placed on the parties," Cantor says. In a separate IDG News Service story, he goes into more detail on that point.

"I obviously can't predict with certainty how the DOJ will react to it, but I think there's a very good chance it will force [Microsoft and Yahoo] to modify the deal at the very least if they do not block it outright. ... Even though it's a partnership, it will be evaluated like a merger ... because Yahoo ceases to be a competitor in search. Yahoo is going to use Bing technology for their sites. I think there's no question the DOJ will come to the conclusion that the deal is anticompetitive."

Brad Smith, Microsoft's general counsel, addressed this question on the conference call last month announcing the deal, saying there's "a compelling case that this is going to increase competition. We anticipate that advertisers are going to recognize the better value that this generates. Web publishers are going to recognize the more innovation this is going to unleash."

He noted that Google has "78 percent of the market worldwide for paid search. I don't know of any other instance where a company with that kind of market share has ever sought to oppose a deal where two smaller companies come together."