The Light Blues were deserving 2-1 winners after the midfielder’s stunning winner 10 minutes from the end of this afternoon’s tie at Ibrox.
Given Saints had already played three league games and this was a young Gers side’s first competitive match, the Perth outfit might even have been expected to win by some.
But it was an inexperienced home team which used nine 16 and 17-year-olds and only four players aged 18 that came out on top and that delighted matchwinner Murdoch.
He said: “St Johnstone had quite a few players who have been involved with their first team so they had quite a lot of experience compared to us.
“But we did well and considering they’ve already been playing, it’s good for us to get the result.
“It shows everyone we’re not going to fall behind just because we’re not in the under-20 league any more.”
Murdoch was particularly happy with the way he and his team-mates were able to rally after Saints levelled with 15 minutes to go.
Callum Gallagher had put the hosts ahead with 17 minutes on the clock but the visitors were able to make it 1-1 through Liam Caddis after growing in confidence as time went on.
Now Murdoch has the same hopes and expectations of Rangers youth sides in the past after the club reached the final each year between 2007 and 2011.
He added: “To be fair to St Johnstone, they scored a decent goal and I thought we did well to get in front of them again.
“Now we want to go as far as we can. We didn’t do well in the competition last season but this time around I feel we can go quite far.
“We want to keep our standards high. We’re just trying to keep ourselves fit, get games under our belts and see where it takes us.”