Just days after Google announced its plans to purchase DoubleClick, the number-one player in the non-search online advertising market, Microsoft representatives publicly asked the US government to intervene. Although no formal complaints have been made to US or international antitrust regulators yet, Microsoft issued a statement noting that the Google-DoubleClick deal will let Google monopolize online advertising.

"This proposed acquisition raises serious competition and privacy concerns in that it gives the Google DoubleClick combination unprecedented control in the delivery of online advertising, and access to a huge amount of consumer information by tracking what customers do online," Microsoft General Counsel and Senior Vice President Brad Smith said. "We think this merger deserves close scrutiny from regulatory authorities to ensure a competitive online advertising market."

Google announced its intention to purchase DoubleClick for $3.1 billon on Friday. The company beat out Microsoft, Time Warner, and Yahoo!, which were jockeying to purchase DoubleClick as well.

Google said that Microsoft's complaints are baseless. "We've studied this closely, and their claims, as stated, are not true," Google CEO Eric Schmidt told "The New York Times."

Microsoft and Google have butted heads in the antitrust arena before. In 2006, Google complained to antitrust regulators in the United States and Europe that Microsoft Internet Explorer (IE) 7.0 didn't make it easy enough for users to change their default search engines to Google. However, regulators found that IE 7.0 was consumer-friendly and made changing the default search engine simple.