Change continues under Marissa Mayer's watch as Yahoo will soon prohibit users from logging into the company's various web services with their Facebook and Google user IDs. Instead, Yahoo visitors will need to sign up for a Yahoo ID to gain access to its various web services.

Yahoo Sports Tourney Pick'Em, a service that lets users select a bracket for the upcoming NCAA college basketball tournament (with the chance to win a billion dollars for a perfect bracket), is the first property to require a Yahoo ID for login. The revised sign-in process for the pick'em started earlier this week on Monday, we're told. Other services like Flickr are expected to follow suit until all services have converted to the new method.

In a statement on the matter, Yahoo said the change will allow them to offer the best personalized experience to everyone. A spokesperson said the Facebook and Google sign-in buttons will eventually be removed from all Yahoo properties although a timeline for the change wasn't provided.

Public relations jargon aside, Yahoo is likely interested in collecting more targeted data about its users. Such knowledge will no doubt allow the company to receive better rates with advertisers and help them determine which services are most popular among its users as well as make it easier to follow a user's activity across multiple services.

Yahoo only started allowing third-party logins in 2010, or in other words, not all that long ago.