We kid you not: Yahoo! (Nasdaq: YHOO) is legitimately eating into Google's (Nasdaq: GOOG) market share in search.

Investors have been right to question Internet traffic-watcher comScore (Nasdaq: SCOR) in recent months. Its reports were being tripped up by contextual links on Yahoo! and Microsoft's (Nasdaq: MSFT) Bing, which the service counted as search-query links. Whatever its intentions, the practice inflated the traditional search queries at Google's expense.

So comScore cleaned up the problem, introducing an "explicit" metric to weed out the contextually-driven clicks. But believe it or not, Yahoo! is gaining ground on Google on that level, too.

Let's look at comScore's explicit market share numbers for July relative to June, including the results of IAC's (Nasdaq: IACI) Ask.com and AOL (NYSE: AOL).

Search Engine

June 10

July 10

Google

66.2%

65.8%

Yahoo!

16.7%

17.1%

Bing

11.0%

11.0%

Ask.com

3.8%

3.8%

AOL

2.4%

2.3%

Source: comScore.

Naturally. Google won't lose any sleep over this. Yahoo! is a speck in Google's rear-view mirror. However, I know that I can't be the only one surprised at how the big three fared sequentially.

  • Google has spent the past few years gaining market share. That growth hasn't always been a straight line, but a setback like this is nonetheless newsworthy.
  • … But perhaps not as notable as Yahoo!'s gain in market share. Once it decided to outsource its paid search to Microsoft in exchange for lucrative payments, I figured that the popularity of Yahoo!'s search engine would gradually fade away. For now, it hasn't.
  • Meanwhile, Bing seems to be hitting a brick wall. It took skeptics by surprise last year with some truly nifty features and an aggressive advertising campaign. Thus, it's shocking to find Yahoo! the only search engine in the big three to actually gain share last month.

Yahoo!'s not the only big winner in these results. Apparently, comScore has managed to fix an analytical shortcoming that was jeopardizing its credibility. It needed this kind of news almost as badly as Yahoo! did.

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Longtime Fool contributor Rick Munarriz is a huge fan of all portals and search engine. He does not own shares in any of the stocks in this story. Rick is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.