The midfield playmaker was part of the Dundee United side which claimed a 3-1 victory over Gers at “neutral” Ibrox two years ago.
The 24-year-old struck the opening goal to send the Tangerines on their way to a final showdown with St Johnstone.
Ultimately, there was only disappointment at Parkhead as the Perth men claimed the trophy in the showpiece showdown.
But Armstrong says the experience of taking on the Light Blues in the last four crunch tie will be invaluable to him, especially considering the fact he has never even been to an Old Firm match, far less played in one.
The former Scotland Under-21 skipper said: “I was cup-tied for last year’s Scottish Cup semi-final against Inverness but played the year before for United against Rangers at Ibrox.
“That was a great game for us. I scored and it was an all round great day. If we could experience those sort of emotions again this weekend it would be great.
“It’s useful that you have experienced these kind of big games before, those pressurised games. This one will be slightly different but again the stadium will be full, so it’s nice I’ve had that experience before.”
Rangers boss Mark Warburton has tried to downplay the significance of the Hampden clash by telling his players to approach the match like they would any other game.
But Armstrong is already anticipating a special occasion ahead of what he hopes will be his derby debut:
“I don’t think you can treat it like any other game because it’s not,” he insisted. “It’s a big tie, a chance to get to the final. It’s Celtic against Rangers.
“I think it will be a good experience. It’s something I’ve never seen live, something I’ve never experienced before. It’s exciting.
“I haven’t given it too much thought what it will be like. I haven’t really had a chance to speak to the other guys who have played in them before. We’ve been focusing on winning league games and increasing that gap on Aberdeen.
“But I’m sure there will be a bit of chat about that this week leading up to the game.
“I think it will be a good game with lots of chances. They like to score goals and so do we, so I’m sure it will be a good one to watch.”
Parkhead defender Mikael Lustig claimed on Tuesday that because Celtic had the “better players and the better team” they would face the pressure that comes with the favourites’ tag.
But newly-crowned Ladbrokes Championship winners Rangers will have to cope with the burden of expectation too as they chase a trophy treble, according to Armstrong.
He said: “I would say there is pressure on both sides. It’s a pressurised game, it’s a semi-final. It’s a chance to get into the final of the Scottish Cup, the biggest cup competition in the country.
“So there will be a lot of pressure on both sides and a lot of expectation.”
Hampden chiefs have faced criticism this week after deciding to install a new pitch at the national stadium just days before it hosts both cup semi-finals.
It is the second new surface to have been put down since the Hoops lost out to Ross County in the last four of the League Cup just two months ago.
Now the football powers have faced calls to opt for a more radical solution than relaying the turf every time it cuts up, such as copying Scottish rugby bosses who installed a £1.2million hybrid surface at Murrayfield when parasites turned the Edinburgh venue’s pitch into a quagmire.
But Armstrong has backed the patch-up job, saying: “The pitch was in a bad condition the last time we were there against Ross County. It was a bit poor and didn’t allow for a passing game as it was so heavy.
“So I’m pleased that it’s being relaid.
“You would like it to be in good condition all the time but that is subject to the weather and the fact Queen’s Park play there regularly. But as long as it is in good nick on Sunday I’ll be happy.”
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