US yields stabilized below 14-year highs. Crude oil found its footing around one-month lows, but remained on course for a second weekly decline amid a firmer dollar and simmering China-centered worries about global growth.

Meanwhile, the People's Bank of China set a much stronger-than-anticipated official mid-point for the yuan - something it has done every day this week - to keep a floor under its currency amid the strains from a robust dollar and a sputtering economy.

MSCI's broadest index of Asia-Pacific shares sagged 1.2 percent, but remained on track for a 0.5 percent gain for the week, which would snap a three-week run of declines.

Nerves ahead of Powell's speech at the Fed's annual retreat for global central bankers, including the Bank of Japan's Kazuo Ueda and European Central Bank's Christine Lagarde, encouraged traders to cash in on the tech-led rally after chip designer Nvidia's extremely strong financial results following Wednesday's closing bell.

The tech-centric Nasdaq slumped 2.2 percent to lead losses of more than 1 percent across Wall Street's three major indexes, and futures indicated a flat start at the reopen.

Japan's Nikkei tumbled 2 percent, with Nvidia supplier Advantest the biggest drag, crashing almost 10 percent.

Hong Kong's Hang Seng slid 1.1 percent, with a tech subindex dropping 1.7 percent. Mainland blue chips drooped 0.4 percent.

"It's all down to Powell," said Matt Simpson, a senior market analyst at City Index.

"In all likelihood, he'll peddle the 'higher for longer' narrative which is likely already priced in, and that leaves the potential for a 'buy the rumor, sell the fact' response," Simpson said.

"However, there is also no real reason for Powell to strike a dovish tone," he added, "and that could mean an ugly end to the week for stocks, while the dollar shines."

The Fed has been raising rates since March 2022 in an effort to bring down inflation, and investors are looking for clarity on whether more rate increases are ahead and how long the Fed plans to hold rates high.

Philadelphia Fed President Patrick Harker set the stage in an interview with CNBC on Thursday, saying he doubted the central bank will need to raise rates again, but also indicated he was not ready to predict when rate cuts might begin.

The US dollar index - which measures the currency against a basket of six developed-market peers, including the euro and yen - pushed as high as 104.20 in Asia, a level last seen in early June.

The euro sank to the lowest since mid-June at $1.07845.

Against Japan's currency, the dollar edged back toward last week's nine-month high of 146.545, last trading at 146.15.

Tokyo consumer price data on Friday, which front-runs nationwide figures, showed inflation remained well above the BOJ's target, but slowed for a second straight month, implying less pressure on the BOJ to imminently tweak policy again.

The Japanese government bond market was quiet, with the benchmark 10-year note yet to change hands on the day. The yield retreated to 0.645 percent on Thursday after hitting a 9-1/2-year peak of 0.675 percent in the previous session. The BOJ unexpectedly doubled the de-facto policy cap on the yield to 1 percent at the end of last month.

Equivalent US Treasury yields ticked up in Asia time, last sitting at 4.245 percent, off the previous session's low of 4.174 percent but well back from Tuesday's peak of 4.366 percent, the highest level since November 2007.

The Chinese yuan traded slightly weaker in offshore markets, slipping 0.07 percent to 7.2866 per dollar. For the week though, it has firmed about 0.28 percent, pulling away from Thursday's 9-1/2-month trough of 7.349.

On top of strong signalling with the official mid-point, the PBOC was also directing domestic banks to scale back outward investments, shrinking the supply of yuan overseas.

In energy markets, crude prices eased further on Friday, staying on track for weekly declines of between 2-3 percent. Brent crude fell 16 cents, or 0.2 percent, to $83.20 a barrel, while US West Texas Intermediate crude fell 18 cents, or 0.2 percent, to $78.91 a barrel.