Source: Michael Kors.

Luxury retailer Michael Kors Holdings (NYSE:CPRI) has turned the fashion world upside down with the impressive way in which it has taken over the accessories space from Coach (NYSE:TPR) and other well-established rivals. Quarter after quarter, Kors has managed to provide the gains in revenue and earnings that growth investors rely on to keep the stock climbing. Yet in its fiscal second-quarter results Tuesday morning, Kors gave investors more to worry about, as the troubling trend of slowing growth in comparable-store sales continued. With the company already having said that its past pace of growth was unsustainable, are Kors shareholders really prepared for a more modest growth outlook in the future? Let's take a closer look at how Michael Kors did last quarter.

The strength of Michael Kors

The fiscal second-quarter results from Michael Kors looked strong on their face. Total revenue soared to $1.06 billion, up 43% and well above the $979 million that investors had pegged. Earnings per share came in at $1.00, beating the consensus by more than a dime per share, and even if you adjust for the hit that Kors took from negative currency adjustments, its results nevertheless were better than most had hoped.

Looking more deeply into the numbers, Kors continued its trend of capturing its strongest growth from its overseas markets. North American revenue climbed almost 30% and still represents the bulk of Kors' total sales, but with comparable-store sales gains of just 10.8%, North America is no longer the biggest opportunity Kors has to expand. By contrast, sales more than doubled both in Europe and in Japan, with European comps climbing 41% and Japanese same-store sales rising nearly 53%.

CEO John Idol was pleased with the company's results. As Idol sees it, Kors offers its "fashion leadership, aspirational product offering, and jet-set luxury image that continue to resonate with customers globally." Pointing to exceptional growth in sales and income, Idol believes that Kors will sustain its momentum going forward as it keeps its global expansion moving forward.

Source: Michael Kors.

Nevertheless, most of Kors' growth came from the 121 new stores that the company has opened over the past year. As the company had predicted, comparable-store sales fell into the teens with gains of 16.4%.

Will Kors keep slowing down?

It's the slowdown in comp growth that most investors focused on in sending shares down 9% in premarket trading after the earnings announcement. In its guidance for the current quarter, Kors projected that its revenue would come in between $1.27 billion and $1.3 billion, which would be at the low end of what most investors expect from the retailer. Earnings guidance of $1.31 to $1.34 per share for the quarter also represents a small reining-in of expectations, and Kors is now calling for low double-digit comp growth that would represent further slowing.

Source: Michael Kors.

Kors' full-year guidance was a bit more mixed, though, as the impact of the retailer's expansion offset weakness in comps. Last quarter, Kors said it expected total revenue for the year of $4.25 billion to $4.35 billion, with earnings expected to be $4 to $4.05 per share and comps showing growth in the high-teens on a percentage basis. In its latest report, Kors boosted its sales guidance to $4.3 billion to $4.4 billion, and it now expects higher earnings to $4.13 to $4.18 per share. But it reduced its comps guidance to the mid-teens, showing its increased reliance on store expansions to produce growth.

For long-term investors in Michael Kors, the hardest part of evaluating the company's future is assessing whether the retailer will ever regain upward momentum in its comparable-store sales growth. When you look back a few years, Michael Kors has seen comps growth fall in a predictable pattern. In order to regain some of its past glory, Kors will have to look at boosting its international presence and taking advantage of greater opportunities overseas to capture untapped markets and boost its financial strength.