* ADP report a tick below expectations, Dec. revised lower
* Tableau Software soars after earnings, outlook
* Merck shares up after results
* Futures off: Dow 43 pts, S&P 8 pts, Nasdaq 12 pts
NEW YORK, Feb 5 (Reuters) - U.S. stocks were set to fall at the open on Wednesday after a slightly disappointing reading on the private labor market and ahead of data on the services sector.
* The U.S. private sector created 175,000 jobs in January, slightly below the expectation of 180,000, while the data for December was revised lower to 227,000 from 238,000. December's data widely overshot a broader report from the Labor Department which showed just 74,000 jobs were created in December. The market-moving government report is due Friday.
* U.S. data is being closely watched after a weak reading in the factory sector on Monday sent Wall Street into a tailspin and triggered a global equities selloff.
* At 10 a.m. (1500 GMT) ISM will report its non-manufacturing PMI for January. Economists expect a slight acceleration in the pace of growth to a reading of 53.7 from 53 in December.
* The limp data earlier in the week added to concerns about growth in China and over the outlook for some emerging market economies. A recent rout in emerging currencies spurred some central banks to act, pressuring bond and stock holdings and luring investors into assets perceived as relatively safe, like the yen, and U.S. and German government debt.
* U.S. stocks rebounded on Tuesday, buoyed by encouraging earnings, as the market attempted to steady in the wake of its largest selloff in months on Monday.
* S&P 500 e-mini futures fell 8 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures fell 43 points and Nasdaq 100 futures lost 12 points.
* Merck shares rose 1.4 percent in premarket trading after the Dow component reported sales and profit that just missed analysts' estimates.
* Shares of Tableau Software jumped 12 percent premarket after the data analysis software maker forecast better-than-expected revenue for this quarter and reported results that handily beat analysts' estimates.
* Shares of Cognizant Technology Solutions fell 4.9 percent before the opening bell. The IT services provider forecast slower-than-expected revenue growth after fourth-quarter results that matched market estimates.
* Designer clothing company Ralph Lauren Corp reported a 10 percent rise in third-quarter profit, helped by higher sales at its own stores, sending its shares up 5.1 percent in premarket trading.
* CVS Caremark Corp said Wednesday it would stop selling tobacco products at its 7,600 stores by October, becoming the first U.S. drugstore chain to take cigarettes off the shelf. Its shares fell 2.3 percent in premarket trading.