* EPS $0.75 versus market estimate of $0.78
* Same-store sales up 1.5 pct in U.S., down in Canada
* Shares drop 5 percent (Adds analyst's comment, details; In U.S. dollars unless noted)
TORONTO, Aug 30 (Reuters) - Alimentation Couche-Tard Inc (ATDb.TO), Canada's top convenience store operator, posted a 10 percent rise in quarterly profit on Tuesday but missed market estimates due to higher motor fuel prices and intense competition, sending its shares lower.
Merchandise sales at stores open for at least a year, a key measure for retailers, were up 1.5 percent in the United States and down 0.2 percent in Canada.
The company said it was facing greater competition in Canada, where pharmacies and department stores increasingly compete with grocers and convenience stores for a slice of the food pie.
Couche-Tard, which competes with 7-Eleven, owned by Japan's Seven & I Holdings (3382.T), and Pantry Inc PTRY.O in the United States, has been faring well south of the border and gaining share at the expense of smaller independent stores struggling to stay afloat.
The company's U.S. margins were higher because of its fresh food and food service offerings, Canaccord Genuity analyst Derek Dley said.
Couche-Tard, whose $2 billion takeover bid for U.S. rival Casey's General Stores (CASY.O) collapsed last year, is still trying to expand in the United States and is in the process of acquiring 33 stores in southern Louisiana from Exxon Mobil Corp (XOM.N).
Earnings for the company's fiscal first quarter, ended July 17, rose to $139.5 million, or 75 cents a share, from $126.9 million, or 67 cents a share, a year earlier. Revenue rose to $5.18 billion.
Analysts, on average, had forecast earnings of 78 cents a share on revenue of $5.46 billion, according to Thomson Reuters I/B/E/S.
Couche-Tard stock, up 29 percent since the start of the year, shed 5 percent and was at C$28.12 on the Toronto Stock Exchange on Tuesday afternoon.
($1=$0.98 Canadian) (Reporting by S. John Tilak; editing by Peter Galloway)