An August rebound in U.S. payrolls would all but cement a Federal Reserve interest-rate increase this month. Yet investors will probably retain doubts about another hike this year, barring a surprise acceleration in wages.

Employers added 198,000 workers last month after 157,000 in July, helping to trim the jobless rate to 3.8% to match the lowest level since 1969, according to a Bloomberg survey ahead of Labor Department data due Friday. Average hourly earnings likely rose 2.7% from a year earlier for a third straight month, only slightly above the 2.5% average in 2017.

While low unemployment and a solid economy mean a September interest-rate hike is a near lock, lackluster pay is among reasons why investors aren't fully convinced the Fed will deliver on its outlook for a fourth 2018 hike in December. There's also an escalating trade war, turmoil in emerging markets and the risk that Fed rate increases will push short-term Treasury yields above long-term rates — the so-called yield-curve inversion that preceded previous recessions.