The Golden Arches are starting to lose some of their shine.
McDonald's Corporation said that a key revenue figure came in flat in July as US consumers pulled back amid a tough economy.
After years of outperforming expectations, even through the recession, the slowdown is the latest sign that the world's biggest hamburger chain is starting to feel the effects of the global economic volatility.
In the US, its promotions failed to drive growth and revenue at restaurants open at least 13 months dipped 0.1%.
The Illinois-based company also says it faced a tough comparison from a year ago, when it launched the mango pineapple smoothie. The figure dipped 0.6% in Europe because of weakness in Germany and several southern European markets.
It also fell 1.5% in the Asia Pacific, Middle East and Africa region - a key growth area for McDonald's. Sales in Latin America and Canada, which are not reported separately, helped pull overall results even with last year.
Revenue in restaurants open at least 13 months is a key measure of a restaurant chain's performance because it excludes the impact of recently opened or closed stores. It does include the company's temporarily closed restaurants.
The figures are a snapshot of money spent on food at both company-owned and franchised restaurants and they do not reflect corporate revenue.
In economically hard-hit regions, such as Europe, McDonald's has been working to emphasise the value of its meals to get penny-pinching consumers to eat out more often. The company noted last month that consumers are pulling back more in light of the weak economy.
McDonald's has exceeded expectations in recent years in large part by emphasising value and continually evolving its menu to keep up with changing tastes.
But now the company is also facing stiffer competition from newcomers such as Panera Bread and old rivals such as Burger King Worldwide and Wendy's, which are revamping their menus and marketing to win market share.
Last month, McDonald's said its net income fell 4% in the second quarter as unfavourable currency exchange rates and high costs ate into profits.
