Inih Effiong’s second-half stunner saw Whites win in sweltering conditions on Saturday afternoon.
The striker lobbed over home stopper Jamie Butler as Dover registered their fifth consecutive victory in the National League, dating back to April.
Jamie Collins’ fierce free-kick on the stroke of half-time had cancelled out Ricky Modeste’s early opener as Athletic moved up a place to sixth on the league ladder.
David Ajiboye lashed over early on following a cross from the Sutton left.
The home side were made to rue their early missed chance when Modeste fired Dover ahead after 10 minutes.
Athletic’s winger beat the Sutton defence to Jai Reason’s free-kick to prod the ball into the top corner.
Steven Rigg stabbed Josh Passley’s pass into the side-netting and Kevin Lokko headed Reason’s corner into the arms of home keeper Butler as the visitors went in search of a second.
Away goalie Lee Worgan dived low to stop Harry Beautyman drilling in an equaliser after the Dover defence failed to clear a ball into the area.
Omar Bugiel directed his header straight at Worgan and at the other end Jason Goodliffe’s weak back header let in Effiong, only for Butler to spread himself in front of Athletic’s striker to stop the ball going in.
Sutton top scorer Beautyman looked to add to his tally of three league goals this season, heading off target and then firing a deflected effort wide of the mark.
Butler then pulled off a stunning save to tip over Effiong’s fierce volley and his opposite goalkeeper Worgan was equally impressive, palming away Ajiboye’s curling effort.
Rigg rose highest to meet Modeste’s corner, only to see the ball land on the roof of the net once the frontman got back to his feet.
However, Sutton levelled on the stroke of half-time as Jamie Collins fired a free-kick into the top corner from just outside the area.
With the restart barely minutes old, Whites went ahead thanks to Effiong’s third goal in as many games.
After Worgan somehow saved from Beautyman following pinball in the Dover penalty area, Effiong hooked the ball over a stunned Butler and into the top corner having been too strong for right-back Dale Bennett.
Parity was almost restored as Rob Milsom’s swirling free-kick flashed past Worgan and his crossbar.
Effiong blasted into the side-netting and with five minutes remaining, forced Butler into a flying save after latching onto sub Alfie Pavey’s through ball.
Effiong nearly sealed the win late on, but Dover held on to move up to sixth on the ladder.
Earlier, boss Hessenthaler made four changes to the side that started against Torquay last week. Cumberbatch, Modeste, Michael Woods and Josh Passley came in for Oscar Gobern, Pavey, Jack Munns and the injured Bobby-Joe Taylor.
Whites next host Woking on Bank Holiday Monday 26th August, kick-off 3 pm.
DOVER ATHLETIC REACTION
SUTTON UNITED REACTION