Marc Richards scored the first goal Accrington had conceded on the road in the league this season to send Port Vale to the top of the table with a 2-0 win.
The visitors made a positive start and should have taken a second-minute lead when defender Phil Edwards spooned an eight-yard volley over the top. But Vale gradually assumed control and Justin Richards went close before Marc Richards ended Stanley's excellent defensive record with a 31st-minute stunner.
John McCombe's header was flicked up by the outside of Tommy Fraser's right boot and Richards netted a sumptuous 20-yard volley for his seventh goal of the season.
Vale were close to extending their advantage when Marc Richards found Justin Richards who sent a left-foot shot inches over the top.
Accrington, to their credit, were excellent at the start of the second-half when Edwards' header tested Stuart Tomlinson before Sean McConville fired over from close range.
But Vale sewed up their fourth straight league win in the 81st minute when Jemal Johnson fed follow substitute Louis Dodds to roll a well placed shot past the unguarded Dunbavin.