* Nikkei sheds 1 pct, Topix falls 0.9 pct * Exporters suffer on concerns U.S. 'fiscal cliff' to trigger recession * Isuzu Motors advances after lifting earnings guidance By Dominic Lau TOKYO, Nov 8 (Reuters) - Japan's Nikkei average fell to a one-week low on Thursday, weighed by downbeat investor sentiment on concerns that U.S. fiscal woes confronting President Barack Obama after his re-election could trigger a new recession. Exporters, which are highly dependent on the health of the global economy, headed lower, with Canon Inc, Honda Motor Co and TDK Corp down between 1.5 and 2.2 percent. The sector was also hurt by a firmer yen as investors worried that the U.S. 'fiscal cliff', a mix of tax increases and spending cuts due to extract some $600 billion from the U.S. economy in the new year, could push the United States and possibly the global economy back into recession. Risk aversion saw the yen trade at 79.905 to the dollar on Thursday, up from Wednesday's low of 80.41 yen. The Nikkei dropped 1 percent to 8,884.60, breaking below its 75-day moving average at 8,888.22 but supported by its 25-day moving average at 8,868.42. "It's probably a knee-jerk reaction ... unwind of the potential (Republican challenger Mitt) Romney premium that was built into the market," a senior trader at a foreign bank said, adding that the U.S. 'fiscal cliff' was not a new issue. "I will be very surprised if we see a whole bunch of people turning up to aggressively sell the market, which we do not see in our flows." The trader said his flows were about 1.2 sell order for every one buy order. Overnight, the Dow Jones industrial average lost more than 300 points in a selloff that drove all major U.S. stock indexes down more than 2 percent in the wake of the presidential election as investors eyed the U.S. fiscal debate and the European Commission's forecast that the euro zone economy would barely grow next year. The broader Topix index lost 0.9 percent to 739.16. Other noticeable losers included telecommunication equipment maker Oki Electric Industry Co Ltd and watch maker Citizen Holdings, down 5.9 and 6.6 percent respectively, after they cut their full-year earnings forecasts. But Isuzu Motors climbed 4.9 percent to a near six-month high after the automaker lifted its annual operating profit estimate. As of Tuesday, 59 percent of the 119 Nikkei companies that have reported quarterly earnings so far undershot market expectations, according to Thomson Reuters StarMine. That compared with 54 percent in the previous quarter. The benchmark Nikkei is up 5 percent this year, trailing a 10.9 percent rise in the U.S. S&P 500 and a 10.8 percent gain in the pan-European STOXX Europe 600 index. Still, Japanese equities are slightly more expensive than their European counterparts, with a 12-month forward price-to-earning ratio of 11.3 versus STOXX Europe 600's 11, data from Thomson Reuters Datastream showed. The S&P 500 carries a 12-month forward P/E of 12.6.