Nikkei down 1 pct, autos lead falls on US sales

*Nikkei falls 1 percent, led down by automakers

*Honda, Toyota and rivals hit after weak US auto sales data

*Yamaha extends losses on Goldman Sachs downgrade to "sell" (Adds stocks and comments)

By Taiga Uranaka

TOKYO, Aug 4 (Reuters) - The Nikkei average fell 1 percent on Monday, with Honda Motor (7267.T) and Toyota Motor (7203.T) sliding after weak U.S. auto sales, while other exporters fell on growing worries about the health of the world's largest economy.

Yamaha Corp (7951.T) extended losses and plunged more than 7 percent after Goldman Sachs reduced its rating to "sell" from "neutral" following the musical instrument maker's first-half outlook cut.

"It's a tough start to the week. U.S. consumption is worsening more than expected," said Fumiyuki Nakanishi, group manager of the investment information department at SMBC Friend Securities.

Toyota, whose July U.S. sales fell 12 percent, last month cut its 2008 groupwide global sales forecast due to a pronounced downturn in the U.S. market.

"When Toyota cuts its production, there will be steel, glass and tyres in excess inventory," Nakanishi said, pointing to an impact on a wider range of industries.

The benchmark Nikkei .N225 ended the morning down 133.53 points at 12,961.06. The broader Topix lost 1.4 percent to 1,255.36.

A raft of Japanese corporate earnings reports are due this week, including from Mitsui & Co (8031.T) and Kirin Holdings (2503.T) later in the day.

"I haven't seen any surprises in first-quarter earnings so far. But the outlook (for corporate earnings) is getting worrisome," said Katsuhiko Mori, senior portolio manager at Daiwa SB Investments.

AUTO IN FOCUS

Honda fell 5.2 percent to 3,300 yen and Toyota lost 3.9 percent to 4,430 yen. They were among the biggest drags on the Nikkei.

U.S. auto sales plunged to a 16-year low in July, led by a 27 percent drop at General Motors Corp (GM.N), as high gas prices and tight credit sent the industry into a tailspin. [ID:nN01496226]

The sales decline was steeper than analysts had expected and showed an accelerating downturn in the world's largest vehicle market as Americans abandoned the SUVs and trucks they had favoured for more than a decade.