It was deadlocked at Park View Road until the 72nd minute when the Hawks grabbed the lead when a corner was fired home by Dan Strugnell after the ball was bouncing about in the box.
Strugnell injured himself in the celebration and had to be substituted soon afterwards!
With 5 minutes added on, Welling pushed forward but the Hawks defence held firm.
Dartford kept pace with Havant after a comfortable 3-1 win over Weston-super-Mare at Princes Park.
Alex Brown gave the Darts an early 3rd minute lead that skipper Elliot Bradbrook added to on the half-hour mark.
Top scorer Alfie Pavey wrapped up the points with a third on 77 minutes, rendering Tom Llewellyn`s stoppage time replay as just a consolation for the Seagulls.
The title is between the top two, with Hampton & Richmond Borough heading the play-off contenders with a seven-point advantage over eighth-placed Braintree Town.
But the Beavers were beaten on Saturday, going down to a 1-0 defeat at The Aspect Arena against a Concord Rangers` side who are now eight points clear of the drop zone.
Steve Cawley`s goal just past the hour-mark gave the Beachboys three precious points.
Only three points split fourth-placed St Albans City and seventh-placed Chelmsford City after today`s games.
Like Hampton, St Albans suffered a surprise defeat to second-bottom Whitehawk – and on their own Clarence Park patch too.
It was a real afternoon to forget for the Saints, who fell behind just before half-time when Nassim L`Ghoul volleyed the ball home.
And just 7 minutes into the second half, the Hawks went two-up when a breakaway ended with Olu Adeloye finishing well past Dean Snedker.
Victory was confirmed 14 minutes from time when a mistake at the back led to Gold Omotayo slotting past Snedker.
The win gives the Sussex side fresh hope, although they are still thirteen points behind the safety-mark with just eighteen left to play for.
Hemel Hempstead Town moved to fifth after a 2-1 success against Chippenham Town at Vauxhall Road.
David Moyo gave the Tudors a great start with a goal inside the opening 2 minutes.
Just before half-time, Karl Oliyide doubled the home side`s advantage.
And then on 62 minutes, Moyo bagged his second and Hemel`s third, only for them to lose Ismail Yakubu to a straight red card just 2 minutes later for denying a goalscoring opportunity.
The home side`s keeper Laurie Walker then saved a spot-kick before Dean Evans eventually netted a consolation for the Bluebirds 3 minutes into stoppage time.
Hemel moved above Truro City, who were beaten 2-1 at Treyew Road by East Thurrock United.
Top scorer Sam Higgins proved to be the Rocks` hero with a brace in the 19th and 44th minutes.
Andy Neal replied with less than 4 minutes to go, but East Thurrock were able to enjoy their long journey back to Essex with three points in the bag.
Chelmsford City are level on points with the White Tigers in seventh after winning 2-1 against third-bottom Poole Town at Melbourne Stadium.
But the Clarets had to recover from being behind as early as the 4th minute to a Richard Gillespie effort.
It wasn`t until the 66th minute that Michael Spillane pulled City level and then Scott Fenwick – the Clarets hero on Easter Monday – netted another winner with 15 minutes remaining.
Defeat leaves the Dolphins eight points behind Hungerford Town, who went down to a 1-0 defeat at Bulpit Lane to a Braintree Town side who are two points behind neighbours Chelmsford.
The only goal came after 56 minutes when Dan Thompson netted at the second attempt after his original volley was saved before ricocheting in off defender Alfie Kilgour.
It stretched the Iron’s impressive run to one defeat in six games.
Wealdstone beat Bath City 2-1 at Grosvenor Vale to leave the Romans virtually out of the play-off race, five points behind Chelmsford with only three games remaining.
After leading at half-time, courtesy of a Matt Richards effort on 42 minutes, City conceded a 70th minute leveller to Jake Sheppard and then had Antoine Semenyo sent-off for a second yellow with 10 minutes remaining.
Four minutes later, Tao Olomowfwe scored what proved to be the Stones` winner.
Oxford City moved four points away from mathematical safety as they overcame Eastbourne Borough 2-1 at Marsh Lane.
An own goal from Matt Pickering gave the Hoops the lead on 53 minutes after Sam Nombe crossed towards Rob Sinclair, before Matt Paterson added a second from the spot just 4 minutes later after Reece Fleet was fouled by Sergio Torres.
Yemi Odubade got one back for Eastbourne in the 86th minute. However, City were able to hold one to record an important win.
Bognor Regis Town`s tenure in the National League South is hanging by a thread after they went down to a 3-2 defeat at Evesham against Gloucester City.
The Rocks are sixteen points adrift of safety with only eighteen left to play for.
They made the Tigers endure a nervy finale though after being seemingly out of the contest after goals from Joe Parker after 38 and 56 minutes and Matty Williams 15 minutes from time.
But Ibra Sekajja 10 minutes later and Keaton Wood in the final minute pulled Bognor to within one of the hosts.