Fed officials have helped spur a rally in world equities in recent weeks by taking an increasingly dovish tone regards monetary policy, fuelling expectations they would cut borrowing costs sharply to support a stuttering economy.
But hopes for a deep reduction were dealt a blow on Friday by data showing the US created far more jobs than expected in June. The report sparked a sell-off in stocks and sent the dollar surging.
Powell is now due to appear before both houses of Congress to give his opinion about the state of the world's top economy, which investors will pore over for an idea about his interest rate plans.
Observers said that while a big cut -- of 50 basis points -- has all but been dismissed, the Fed is expected to unveil at least a 25 point reduction at its next gathering this month.
"It's unlikely the Fed would risk ignoring the markets' signalling, especially after taking a dovish turn at the June (policy) meeting, which sparked a broad risk-on rally and overshadowed concerns about slowing US and global growth," said Stephen Innes at Vanguard Markets.
"After all, there is that small thing called 'credibility issues', so why on Earth would the Fed want to lead markets down the primrose path?"
Anna Han, equity strategist at Wells Fargo Securities, took an upbeat view on the outlook.
"Unless you get some huge red flags from the testimony over the next two days, we are going to enter into a more accommodative environment," she told Bloomberg TV. "That's an opportunity to put risk on."
- Oil prices rally -
After a mildly positive lead from Wall Street and two days of selling, Asia investors trod a careful path Wednesday.
Hong Kong edged up 0.4 percent and Sydney rose 0.6 percent and Singapore put on 0.5 percent.
Shanghai added 0.1 percent but struggled for traction after data showed June factory prices were unchanged from a year ago and fell from the previous month, hit by the US trade war.
"The fall in non-food inflation suggests consumption remains weak, which would likely put pressure on regulators to introduce more consumption stimulus," Innes added.
Seoul rose 0.4 percent, while Wellington jumped 0.6 percent and Taipei gained 0.5 percent with Manila and Jakarta also up.
Tokyo ended the morning slightly lower.
Oil prices jumped more than one percent after a closely watched industry report showed a massive drop in US stockpiles last week, while traders also cheered reports that Russian output fell in July to its lowest in nearly three years.
The developments provided a boost to the commodity, which took a hit earlier in the week as a stronger dollar added to ongoing worries about the trade war and soft global outlook.
Still, analysts said prices will remain volatile as investors weigh the trade row against geopolitical tensions in the Middle East.