Then he went on to make a piece of quirky footballing history when he was replaced after 79 minutes by his identical twin brother Jacob, who came off the bench to make his senior debut.
Who said there was no longer any magic in the FA Cup?
The Murphys then went home to have their performances analysed by mum Maxine.
"My mum comes to every game," said Josh.
"And then we go home and she will analyse my game. She tells me how I played 'You didn't do this well or you didn't do that well'. She knows her stuff."
The Murphys have come through the Norwich academy and Josh scored a goal in the club's youth cup final victory against Chelsea last season.
His step up to play with the big boys has been seamless judging by the confidence and competence on show on Saturday when his surging wide play tormented Fulham.
"At least we didn't get knocked out of the cup and all the lads are happy," said Josh, who only discovered he was playing at 11am on the morning of the match.
"When I found out that I was in the starting line-up me and my brother just went in the toilets and quickly gave each other a high five.
"It was a big moment for us. I just thought I had to go out there and do my job. I get the ball and get at people. I'm a confident young player who likes to get crosses and shots in."
Even when the substitutes board went up and Jacob came on there was no sense of disappointment.
"There's no rivalry at all," said Josh.
"When I came off I was happy that he was going on because I know what he is capable of.
"It was crazy. I saw him getting undressed and I knew I was going to come off and when I saw him standing there with a little smile on his face it was like, 'It's your turn now'."
Josh, who admits he studies YouTube clips of Cristiano Ronaldo and Lionel Messi to learn his trade, puts his trust in manager Chris Hughton.
"I wouldn't have imagined me playing now," admitted Josh.
"But he (Hughton) knows what he is doing. He's brought me through like he did with Nathan (Redmond) and he's made almost 100 appearances for the senior team.
"I thought I would be playing for the first team but not maybe for another year and a half, so to be playing now is a great feeling."
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