Outback Steakhouse Inc. (OSI) said on Thursday that sales at its namesake restaurants open at least 18 months fell 0.8 percent in the five weeks ended Dec. 25, weighed down by Christmas being on a Saturday this year.

The company's restaurants were closed on Christmas Day, and Saturday is typically one of the company's busiest days of the week, a spokeswoman said.

Last year Christmas was on a Thursday, which is typically a less busy day, the spokeswoman said.

Same-restaurant sales were up 2.3 percent at Outback Steakhouse (search) restaurants in the first four weeks of the period, the company said.

Same-restaurant sales at its Carrabba's Italian grills (search) rose 3.2 percent in the five weeks ended Dec. 25, the company said. Those sales were 6.7 percent higher in the first four weeks of the period, Outback said.