The Scots had taken a sixth-minute lead through west Cumbrian Kevin Connelly and Reds were subdued for half an hour.
But they burst into life with two goals just before half-time from Sam Joel.
Gretna rang the changes in the second half when Workington generally had the better of things but didn’t score again until the 84th minute through Dave Symington.
It was a worthwhile work out for both sides.
Workington fans had their first opportunity to look at Jamie Mellon, a former member of the Everton Academy.
He had been recommended by Brian Dawson, head of Reds in the Community, who last season pushed Joel Workington’s way.
The home side could have grabbed an early lead when Conor Tinnion sneaked in on the blindside to reach a Symington cross but mishit the shot straight at keeper Craig Murray.
Gretna were close to scoring themselves in the fifth minute. Former Reds winger Kevin Jolly was stopped by a Matty Douglas tackle and, from the clearance, Aaron Kelly hit the bar.
But almost immediately the visitors did take the lead. Reds were caught out by an early ball to find Connelly and he cleverly beat Aaran Taylor with a cool finish on six minutes.
At the other end, Reds were awarded a free-kick when Joel went down in a tackle. Tinnion tried one of his left-foot specials but it dropped just over the bar.
A young Gretna side was holding its own against more experienced hosts.
Mellon was shown to good effect, linking with Joel down the left and pulling back a great cross which flashed invitingly across the Gretna goal.
It sparked a good spell for Reds as they saw plenty of the ball and generally used it well.
But Gretna stood firm with Jordan Little a key figure in the centre of the defence.
Symington had a shooting opportunity on 27 minutes but was just too high. Then a poor clearance by Dylan Atkinson presented James Earl with a chance but he shot tamely at Murray.
Workington drew level on 35 minutes in strange fashion. Aaron Kelly punted the ball 40 yards back to his keeper who could only chest it into the path of Joel. He went on to fire into an empty net.
Five minutes later, Reds went in front with an excellent second goal by Joel.
He started the move with a clever shimmy past a defender, took a quick return pass from Rob Wilson before going on and calmly beating Murray from eight yards.
Gretna made changes at the start of the second half but Reds stayed with the same line-up.
Reds had finished the half well after a mediocre start and they were similarly slow out of the traps second time round.
They were livened up when Earl battled well for a ball in midfield and Tinnion thundered through to curl a low shot just past the upright.
Then, Joel seized on a mistake by Gretna skipper Mathew Read but saw his shot deflected for a corner.
Workington were starting to find their rhythm and a great ball from Joel inside the full-back found Tinnion cutting in but Murray held onto his cross shot.
Matty Douglas, who had been one of Reds' best on the night at right-back, moved into the centre as Dan Wordsworth came off on 64 minutes.
Jake Simpson was the first Reds substitute, joined immediately by Anthony Wright for Rob Wilson.
Gretna boss Matt Henney was ringing the changes with five subs used in the second half.
They had a chance on 72 minutes with a free-kick out on the left-hand byline and Earl produced a fine head clearance to a dangerous cross.
Then, a foul on Tommy Whitehead by Sam Smith brought another free-kick and this time Lewis Jolly’s effort came back off the wall.
Henney sent on his sixth substitute for the final 15 minutes.
Jordan Williams came on for Douglas after 79 minutes and he was soon followed on by Cameron Carter and Ben McDonald.
Five minutes later Reds grabbed their third. Symington drove at the Gretna defence, forced his way through two tackles before thumping a vicious shot past Murray.
Gretna came back and forced a corner when a Jake Smith cross was deflected behind. The ball was eventually cleared after a couple of Gretna headers threatened to cause problems.
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