Touted as a long-term key position prospect when he was selected at pick 57 in last year’s national draft, Johnson has broken through for his first senior game much earlier than he dared hope.

“When I got to Sydney last year I was determined to be as professional as possible and take advantage of all the support that was on offer. I was really looking forward to being a full-time footballer,’’ Johnson told sydneyswans.com.au.

“I really tried to attack the pre-season and I had an aim to play a game this season but it’s come about already and I’m so excited by it. I can’t wait to get out there on Saturday.”

Johnson has been impressive in recent weeks playing as a key defender in the reserves and has been selected to help counter West Coast’s band of tall attacking players.

Coach John Longmire says Johnson has earned the respect of everyone at the Club for his work-rate and attitude over the past six months.

“Alex has been super, his attitude is unbelievable for someone of his age,’’ Longmire said.

“He’s super athletic and very competitive. He’s young so he’s going to make mistakes but we’re looking forward to seeing what he can achieve.’’

Johnson is another product of Melbourne’s Xavier College. On Saturday, the Swans team will include four Xavier boys - Johnson, Dan Hannebery, Josh Kennedy and Ted Richards.

Johnson and Hannebery both did year 12 in 2009 and played in both the school football team and Oakleigh Chargers in the Under 18 TAC Cup.

“Dan was playing for the Swans when we were in Year 12 so he’d fly in and out to Sydney and then come back to school. It was pretty weird at the time!’’, Johnson recalled.

“We also did athletics together and ran the 4x800m for the school.’’

While he was a talented middle distance runner, playing in the AFL was what Johnson really wanted to achieve. Young for his school year, he didn’t nominate for the draft until 2010, and went to Deakin University last year to study commerce and sports management.

In all the fantasy drafts, it was predicted he’d be taken by Collingwood at pick number 45. He was watching at home with his family in Melbourne. “When it got to pick 45, they said ‘Alex..’ but it was another Alex that Collingwood took (Alex Fasolo). I felt sick and had to leave the room because all I wanted was to get picked and Dad was being a bit of a stress head!, ’’ Johnson says.

But he didn’t have to wait long, with the Swans picking him 12 selections later. “I was so rapt to get drafted, it was a massive relief.’’

The club had spoken to Johnson about four times before the draft, with recruiting staff particularly impressed by the defensive work rate he displayed during the Under 18 national carnival.

In that carnival, where he played for Vic Metro, he started as a key forward but was switched into defence and did well.

The move paid off, as that’s where he’s been spending most of his time on the training track and in practice games since he arrived at the Swans.

And it was probably meant to be that Johnson ended up at the Swans. He doesn’t know the finer details but believes his grandfather, also Alex Johnson, may have spent time playing with South Melbourne around the time of World War 2.

The full Swans team for the round 3 game against the West Coast Eagles will be named at 5pm today.