Former Murray Bushranger Mathew Walker, who was a Greater Western Sydney Academy member, joined Hawthorn with the 63rd pick in last year's NAB AFL Draft.
The Hawks sent a future fourth-round pick to Collingwood in return for that selection then swooped on Walker, with the Giants declining to match the bid.
A knee injury held the 19-year-old forward back in his first pre-season with Hawthorn, but he played in the club's opening JLT Community Series against Brisbane on Sunday.
Walker finished with seven disposals, one major and four marks, two of which were particularly sharp and led to Hawk goals.
The performance caught the eye of Hawthorn football boss Graham Wright, who is not one for false praise.
"I thought Mat Walker was really impressive on the weekend and I wouldn't be surprised if he debuts this year," Wright said at the Hawks' season launch on Tuesday night.
Walker himself was pleasantly surprised when he found out he was succeeding four-time premiership player and 2015 Norm Smith medallist Rioli in the No.33.
"It's a massive honour and privilege, but I didn't even know I was going to get that number," Walker said.
"I was sitting in a team meeting – I don't know if 'Clarko' (coach Alastair Clarkson) was behind it – but I was sitting there in a team meeting, in the front row, and I saw the 33 come up and my jaw just dropped.
"It was pretty crazy, but now I just want to make it my own for the next (however long)."