Similar to Saturday, Technical did not impress in the first half as Roslyn won more possession and launched more shots.
Flamboyant striker Geordie Mansford looked dangerous as he partnered Mike Sannum, behind the unflagging running of Fraser Cameron and Damo Foster.
Possibly against the run of play, an explosive break enabled Technical striker Taylor McCormack to burst through, veer left and, from a narrowing angle, he drilled a strong shot past Roslyn keeper Mike Rae.
If anything, the temperature of the match reached sizzling point as both sides battled for midfield possession, and referee Richard Roberts was forced into making more than a few decisions.
Roslyn's Mansford was in electric form, weaving and bobbing past tackles, and it was no surprise when he hit a crisp equaliser after 37 minutes. Both sides battled for supremacy as halftime approached and, in typical cup-tie fashion, the ball might have needed to be carried off on a stretcher at the break.
The match-breaker arrived when Technical was awarded a free kick 25m out, and coach Aaron Burgess summoned his left fullback John Curwen to have a hit.
And what a hit!
The rangy defender left-footed a dipping shot that beat Roslyn's defensive wall and the despairing dive of keeper Rae before rasping inside the right post and bulging the net.
When asked if he was a specialist free-kick taker, the young fullback just shrugged and admitted he had never scored from a set play before.
Coach Burgess then showed his team's strength in depth by bringing on Scots striker Tom McBride, who upset the Roslyn defence with a combination of skill and violence as he made his mark.
At that critical time, Roslyn's tidy midfield became ragged, some passes went astray and, feeding on errors, Technical started to dominate.
It took big McBride five minutes to find space on the right and shoot Technical into a 3-1 lead, and more lost possession had Roslyn scrambling as Alistair Rickerby fed McBride to create a gift one-on-one with the keeper, but that chance went begging.
Judder Flaws had been denying his veteran status with darting runs up the wing, and a switch play created space for the Chatham Cup medallist to show he still had it, as he opted for power and laced an unstoppable shot past Rae for a 4-1 scoreline after 70 minutes.
Both sides put on substitutes in what would predictably be a white-hot finish, and Roslyn pressure forced a congested goalmouth, and a hand ball which had the referee awarding a penalty.
Roslyn captain Aajay Cunningham calmly beat keeper Batty, but there was no panic in the Technical defence, and both sides continued to entertain with aggressive attacking play in which a series of set plays tested character and courage.
Technical coach Burgess congratulated Roslyn on a top match, and praised his own side's mental toughness.
''That's two matches we had to battle back into, first Mosgiel on Saturday, then Roslyn today, so I am really pleased with our team's skill and character."
As a former striker of note, the coach also praised that match-breaking free kick by Curwen.
''He was the only lefty we had, so I called him up to have a go and he delivered.''
Roslyn coach Colin Thom shrugged philosophically.
''We gave it our best shot, and played some really good attacking football. We just didn't hit the net enough, and their keeper Batty was in top form.
''Our player of the day was Geordie [Mansford] for his goal, and for some inspired skills, as he combined with Mike Sannum, and our two frontrunners, Damo [Foster] and Fraser [Cameron].''
In other matches yesterday,
Northern Hearts beat Mosgiel 5-0 at Aorangi Park in Timaru, Otago University downed Old Boys 2-0 at the ILT Turf in Invercargill and Pleasant Point defeated West End 3-2 at West End Park in Timaru.
