The unexpected setback for pay appears to have further dampened the chance of a summer interest rate hike by the Bank of England.
Wage growth weakened to 2.8% in the three months to April though there was a strong increase in the number of people in work, official figures show.
The data from the Office for National Statistics (ONS) shows pay is still increasing more quickly than inflation.
But the pace of regular wage growth - excluding bonuses - has slipped back after reaching 2.9% in the previous month's set of figures - which was the best increase since 2015.
It could further douse expectations of an interest rate hike this summer - already dampened by indications of sluggish economic growth after a first quarter in which the UK slowed to a near standstill.
But there was a better than expected increase in the number of people in work, by 146,000 to 32.39 million, while unemployment fell by 38,000 to 1.42 million and the jobless rate remained at a 43-year low of 4.2%.
Households endured a financial squeeze during most of 2017 as the average increase in wages lagged behind the growth in the cost of living.
The situation began to improve earlier this year as pay overtook inflation again. But the latest slowdown narrows the gap. Official figures showed inflation running at 2.4% in April.
Ben Brettell, senior economist at Hargreaves Lansdown, said the dip in wage growth poured cold water on any hope that the Bank of England's Monetary Policy Committee (MPC) might raise interest rates in August.
Howard Archer, chief economic advisor to the EY ITEM Club, said: "The strong rise in employment is obviously good news for UK consumers but April's moderation in earnings growth highlights the funereal and erratic progress in improving purchasing power.
"We suspect that there is an increased chance that the Bank of England will hold fire on interest rates until November given that the MPC wants to see clear, sustained evidence that the UK economy has improved from its first quarter relapse before hiking."
TUC general secretary Frances O'Grady said: "Wage growth is stuck in the slow lane. At this rate pay packets won't recover to their pre-recession levels for years."