Microsoft’s Xbox 360 has managed to reach the 10 million units sold in the U.S. milestone, being the first of the next-generation’s gaming consoles to achieve this performance.

Even though Microsoft has considered that the console that reaches this milestone is the generation’s champion, the company should not consider the battle over. Nintendo’s Wii is just behind, with only about 500,000 units less.

The Deutsche Bank analyst Jeetil Patel believes that Nintendo will surpass Xbox 360 installed base as soon as next month.

The fact that Microsoft has managed to reach the milestone before its competition is mainly because it has a year on the market ahead of the Wii. The Nintendo console is supposed to reach Microsoft’s sales in less than two months, thanks to the incredible momentum it has on the market, selling an average of more than 700,000 units per month in the last two months, compared to Xbox 360’s 200,000.

According to Patel, the Wii's installed base reached 9.5mn units. Since its launch in November 2006, Nintendo Wii has sold close to 24 million units worldwide.

According to Nintendo’s latest financial results in the past fiscal year, Nintendo has shipped 18.61 million Wii consoles to its distributors and retail customers across the globe.  For the next fiscal year, Nintendo hopes to ship 25 million Wiis.

According to the latest data released by the tracking company The NPD Group, during April Nintendo sold 714,000 Wiis in the U.S. As in May the company is set to release its widely-acclaimed fitness game, Wii Fit, it is believed that Nintendo will match or even surpass the April sales.

In addition, the gaming analysts are predicting an increase of the Xbox 360 and PS3 sales due to the release of GTA IV. The game was launched on April 29 and it could drive the sales of both consoles throughout May.