Wall Street gains lead to lower openings in Asia-Pacific markets; focus on Japan and South Korea data.

• The unemployment rate in South Korea decreased to 2.4% in August, which is the lowest it has been since the data series began in 1999, as reported by Statistics Korea.
• A presidential debate between Republican nominee Donald Trump and Democratic vice president Kamala Harris is scheduled to take place prior to the November US election.

Despite gains on Wall Street ahead of the U.S. August consumer inflation report, Asia-Pacific markets opened lower on Wednesday.

Economic data from Japan and South Korea was analyzed by traders in Asia. Statistics Korea reported that unemployment in August was at 2.4%, the lowest since the data series began in 1999.

In September, the Reuters Tankan survey revealed that big manufacturers' business confidence decreased to a seven-month low of plus 4, compared to the previous month's plus 10. Meanwhile, non-manufacturers' sentiment declined for the third consecutive month to plus 23, down from plus 24 in August.

The first and only presidential debate between Republican nominee Donald Trump and Democratic Vice President Kamala Harris is scheduled to take place, marking their only encounter before the US presidential election in November.

The Federal Trade Commission may investigate its potential deal with Canada's Alimentation, according to two sources, after Seven & i rejected Couch-Tard's proposal, citing U.S. antitrust concerns.

The broad-based Topix was 0.86% lower than Japan's 0.7% decline.

While the Kospi remained relatively stable, the Kosdaq experienced a 1.14% increase.

Australia's S&P/ASX 200 was marginally lower.

On Tuesday, U.S. stocks fluctuated overnight, with two out of the three major indexes finishing in the positive, as traders anticipate an interest rate cut at the Federal Reserve's September meeting to ease economic concerns.

—CNBC's Brian Evans and Pia Singh contributed to this report.