Russia’s largest Internet portal Mail.ru has acquired a 30% stake in its online dating partner Mamba, Quintura reports. They had to pay $15 million for a chunk of the enormous dating service – which offers dating platforms to several big Russian Internet parties.

Mamba has an user base of 10 million people. 1.5 to 2 million of them are looking for the love of their life (or a one night stand) on a daily basis. Together with Loveplanet (which is a destination site), Mamba holds 90 percent of the Russian $21 million dating market.

Not surprisingly, Mamba’s financial numbers are also impressive. The company reported revenues of $9.2 million in the first half of 2008, which meant a 68% percent increase from the first half of 2007.

Mail.ru had to pay the 15 million dollars to Finam, a Moscow-based investment and financial services group that acquired a controlling stake in Mamba in October 2005. It’s their third hit this year, as they recently also sold their stakes in Begun (to Google) and computer game publisher Buka.

There’s interesting twist to this deal

The people at Rambler HQ – that other big Russian web portal – won’t be amused by Mail.ru’s move. Rambler’s dating section uses Mamba’s platform, and accounts for 25 percent of Mamba’s usage. How will they feel about a competitor buying a rather large stake in the same service provider?

If Rambler decides to move its dating section to another platform, the revenue of Mamba could decline by 25 percent. Then Mail.ru will temporarily become a victim of its own deal.