US STOCKS-S&P 500, Nasdaq set for new heights on hopeful coronavirus news

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* Sprint set for best day ahead of ruling for T Mobile deal

* Under Armour slumps after surprise sales drop forecast

* Fed Chair Powell to testify before Congress at 10 a.m. ET

* Futures up: Dow 0.35%, S&P 0.31%, Nasdaq 0.45% (Adds comments, company news and U.S. economy; updates prices)

By Medha Singh

Feb 11 (Reuters) - The S&P 500 and Nasdaq indexes were set to hit record highs at the open on Tuesday as a top Chinese health adviser said the coronavirus outbreak may plateau in the next few weeks, while Sprint shares soared after winning a federal judge's approval for its merger with T-Mobile.

After more than 1,000 deaths and weeks when the outbreak centered in the Hubei province which roiled financial markets, the country's foremost medical adviser on the epidemic said infections may be over by April, with the number of new cases already declining in some places.

For investors trying to get back to a decade-long stocks rally, however, it was still unclear how much of a hit the world's second-largest economy would take as factories struggled to resume production after an extended holiday.

"For the time-being investors are willing to say 'we are going to invest in what we know' and what we know right now is that the U.S. economy is in pretty good shape, earnings have been better than expected and the Fed continues to have our back," said Art Hogan, chief market strategist at National Securities in New York.

Federal Reserve Chair Jerome Powell was fairly upbeat about the outlook for the U.S. economy in his prepared remarks to Congress on Tuesday, but cited a potential threat from the coronavirus and concerns about the economy's long-term health.

His address is expected to begin at 10 a.m. ET (1500 GMT).

Dow e-minis rose 103 points, or 0.35%. S&P 500 e-minis were up 10.25 points, or 0.31% and Nasdaq 100 e-minis rose 43.25 points, or 0.45%.

The S&P 500 and the Nasdaq closed at record highs on Monday as largely better-than-expected quarterly earnings, positive U.S. economic data and China's recent stimulus measures helped investors look past fears about the virus fallout.

Sprint soared 70.4% as a district court judge's decision cleared the path for the deal with T-Mobile US , which was originally valued at $26 billion.

T-Mobile shares jumped 9.6%, while larger rivals Verizon Communications Inc and AT&T Inc rose 0.5% and 0.7%, respectively.

Fourth-quarter earnings have largely been upbeat, with about 71% of the 324 S&P 500 companies that have reported results so far beating profit estimates.

Hasbro Inc climbed 5.8% after posting better-than-expected quarterly profit, boosted by lower costs and strong demand for toys based on Disney's Frozen and Star Wars franchises.

Under Armour Inc tumbled 14% after it forecast a surprise drop in 2020 revenue, partly due to the coronavirus outbreak. (Reporting by Medha Singh and Shreyashi Sanyal in Bengaluru; Editing by Bernard Orr)