* Nikkei heads for worst weekly loss since October * Fast Retailing climbs after strong Q1 results By Dominic Lau TOKYO, Jan 10 (Reuters) - Japan's Nikkei benchmark slipped on Friday and headed for a weekly loss in the first trading week of 2014, though Uniqlo clothing chain operator Fast Retailing Co Ltd surged after its quarterly earnings beat expectations. Fast Retailing climbed 3.5 percent after it posted a higher-than-expected first-quarter profit, helped by strong Japan sales at its flagship casual Uniqlo brand which attracted customers with affordable luxury items. It was the most-traded stock on the main board and the top-weighted gainer in the Nikkei, which eased 0.2 percent to 15,841.85 ahead of the release of the U.S. jobs report later in the day. The benchmark Nikkei was down 2.8 percent this week, on track for its worst weekly decline since October. It surged 57 percent last year to mark its best annual rise since 1972, driven by Japan's massive fiscal and monetary stimulus campaign. "We are quite busy this morning," a Tokyo-based trader at a European bank said, adding that buy orders outpaced sell tickets by two to one for his firm. He said long-only investors and hedge funds were active and buying across the board but with smaller lot size. "The absolute value term is a bit lower today. I guess we have the nonfarm payrolls coming out tonight," he added. The U.S. nonfarm payrolls report, due out later in the day, will further signal how the world's largest economy is faring - and therefore, how fast the Federal Reserve will dial back stimulus. Economists polled by Reuters have forecast 196,000 jobs were added to the U.S. economy in December. Mitsubishi Materials Corp dropped 1.9 percent after an explosion at a chemicals plant in western Japan on Thursday, while its customer Sumco Corp lost 2 percent. But Dainippon Sumitomo Pharma surged 12.3 percent to an eight-month high after U.S.-listed Intercept Pharmaceuticals Inc said it could conduct a late-stage trial with the Japanese firm for a drug to treat liver disease caused by fat buildup. The drug was found effective in a trial. It was the second top-weighted gainer in the Nikkei after Fast Retailing. The broader Topix index was down 0.5 percent at 1,290.88, with volume at X percent of fully daily average for the past 90 trading days, while the JPX-Nikkei Index 400 , which started trading on Monday, shed 0.5 percent to 11,648.70. In terms of valuations, Japanese equities carried a 12-month forward price-to-earnings of 14.7, below a 10-year average of 16 and the U.S. S&P 500's 15.3, data from Thomson Reuters Datastream showed.