Google+ has become the fastest growing social media site and perhaps the fastest site, period, but last week's inflection point in growth highlights the uphill battle it will need to fight to cement itself as No.1.

Google's social-network received more than 1.79 million total visits during the week ending July 23, representing a three percent decrease from the week before, analytics firm Experian Hitwise found.

But Matt Tatham of Experian warned that the numbers represent just a short time frame and should be taken lightly.

"It's really small," Tatham said with regards to the drop. "Just keep it in context, we're just a month in. Out of the gate they had a good start."

Traffic to Google+ already grew the first few days of this week, he noted.

The Facebook Factor

Relations between Facebook and Google have soured in recent years as the technology partners have grown into bitter rivals competing to swoop up the online advertising space.

Google's direct entry into the social networking arena only exacerbates that.

But beyond the obvious consumer realm, the next biggest thing could be a social networking space for businesses. To date there's only one social network that has had success in this area, LinkedIn, which saw an $8 billion IPO in May.

Google has already shown its inclination to go into business networking, saying its service would be "amazing" for businesses. They key was it would happen at a later date, so Google deleted profiles of businesses off Google+, causing a mild uproar that Facebook happily milked.

Facebook rolled out "Facebook for Business," which teaches companies how to use the site's "powerful marketing tools" to create a Facebook Page, build relationships with members of the Facebook community, and use Facebook Ads and Sponsored Stories.

While not necessarily being new, as businesses already use Facebook, the announcement focused on how businesses could further take advantage of Facebook. The timing, however, perfectly highlighted Google's stumble.

Broader Challenges

The decline, however small, shows the challenges Google faces as it attempts to break into the already crowded social networking space.

While Google+'s rate of growth is unrivaled, the social network is still small in comparison to mature rivals Facebook and Twitter, which have 750 million and 200 million registered users, respectively.

Google also needs to take steps to ensure that its new offering doesn't follow the same fate as its predecessors: Google Buzz and Google Wave.

While those sites saw initial interest, participation waned and the projects were eventually pulled.

"[Google+'s] ultimate success will depend on how well it converts this strong trial base into regular users," ComScore's Andrew Lipsman warned.

Indeed, while rivals like Facebook and Twitter have become online destinations in themselves, over 50 percent of traffic coming to Google+ originates from Google or Gmail.

Facebook also enjoys stronger user engagement than Google+. In the increasingly competitive digital marketing environment, advertisers are concerned with not only reach and targeting, but also how long users are interacting with the site.

The time users spent on Google+ saw a decrease last week by 10 percent, with users spending an average of 5 minutes 15 seconds on the site.

"The 10 percent drop seems somewhat big, but in reality it is not," Tatham said, saying he believes that would "continue to grow."

In comparison, Facebook users on average spend 55 minutes on the site per day, according to Facebook's self-reported statistics.

And while Google CEO Larry Page told investors the site has already amassed 10 million users, HitWise data indicates that just 10 percent of those registered visit the site.

With strong integration to Google's ecosystem of products and services and plenty of hype, Google+ will have little problem reaching more people.

The challenge will be converting them from passers-by to dedicated users.

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