Lululemon has upgraded its guidance for the quarter running to the end of January on the back of robust sales during the holiday season. The Canadian yoga apparel company said the uptick had been driven by strong execution in stores and online during the key holiday weeks. While sales were above expectations, gross margin rates and expenses were in line with previous guidance. The company predicts that its sales will end up in the range of $690 million to $695 million for the fourth quarter of its fiscal year, which is an increase of about 15 percent compared with the same quarter in the previous fiscal year. It amounts to a rise of 19 percent in constant currencies. The company had previously forecast sales of around $670 million to $685 million. The upgraded forecast calls for a comparable sales increase at a high single-digit rate in constant currencies, up from a mid-single-digit rate comparable sales increase in its previous guidance. The forecast for diluted earnings per share was also increased from a range of $0.75 to $0.78 to a range of $0.78 to $0.80 for the quarter. The upgrade came just a month after Lululemon reduced its sales forecast for the full year.