In a prior article, I wrote about the fantastic long-term growth prospects of Under Armour (NYSE:UAA) and why I believe the company is destined to be the athletic apparel brand of the future, possibly even challenging industry stalwart Nike (NYSE:NKE) on the global stage.

After Under Armour's latest third-quarter earnings report, all my bullish sentiments have been confirmed. However, the stock's post-earnings reaction has created something of a dream scenario for investors, and it is one that will not last long.

The report
The company reported fantastic results all around. Net revenue increased 26% quarter over quarter to $723 million, which beat the average analyst estimate of $709 million. This growth was primarily driven by Under Armour's largest product category, apparel, which grew 26% and managed to log its 16th straight quarter of growth above 20%. Footwear revenue increased 28% to $81 million, and now makes up approximately 11% of the company's total revenue.

Most impressive on the revenue front was the fact that Under Armour grew international sales 38% to $44 million, which still accounted for only 6% of total net revenue. This is important because management recently made it a priority to focus on international markets.

The small percentage of revenue that the segment currently accounts for highlights the tremendous opportunities available to the small American company. While it is not yet a global threat to Nike, the potential for Under Armour to grow internationally is massive.

The company's net income increased 27% to $72.8 million, or $0.68 per share, which beat the average analyst estimate of $0.66. The company's cash increased 19% to $186 million, and long-term debt decreased 25% to $54 million.

The Nike comparison
These results compare favorably to Nike's most-recent earnings report. On a year-over-year basis, Nike reported solid revenue growth of 8% and robust earnings-per-share growth of 37% in its most-recent quarter. The company's future orders were also up, and indicate that more strength is likely to continue.

However, analyst estimates call for Under Armour to grow revenue 22% and EPS 24.3% next year, while Nike is expected to grow revenue just 8.7% and EPS 16.1%. Also, simply by taking a look at the revenue for both companies, it is easy to see that Nike has a much larger footprint than Under Armour, which is both a good and bad thing. It means Nike is more diverse and less dependent on individual markets. It also means Nike is not capable of expanding in the same aggressive way that Under Armour can.

The guidance
Since I have owned shares of Under Armour for years and have listened to every one of the company's conference calls, I have come to expect rather conservative guidance from management. However, this time management raised the company's 2013 outlook. Management now expects fiscal 2013 revenue to come in at $2.26 billion, which is up from prior estimates of $2.23-$2.25 billion and represents growth of 23%. Management also expects a higher operating income of $260 million, up from the prior estimate of $258 million.

The reaction
Even with a beat on both the top and bottom lines and raised guidance, shares of Under Armour still traded down on the day of the company's report. Shares are now off approximately 6.7% from its all-time highs, and present investors with a better entry point.

Had the stock not rallied into earnings, shares of Under Armour would have no doubt popped on the day management announced such impressive earnings and guidance. Still, an earnings beat and raised guidance, combined with a declining share price, equals opportunity for investors.

Conclusion
Under Armour and Nike recently reported solid performance, which indicates the athletic apparel/footwear space is generally strong. You should be able to do well with either company, although Under Armour is definitely where the aggressive growth is at. Aside from valuation concerns, and a frothy market, there is no reason why Under Armour should be down after reporting such a strong quarter. As such, you should consider the stock, despite its current weakness.

Philip Saglimbeni owns shares of Under Armour. The Motley Fool recommends Nike and Under Armour. The Motley Fool owns shares of Nike and Under Armour. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.