The no. 3 pick from the 2010 NAB AFL Draft has taken his game to a new level in 2013 and has averaged a goal in each of his three games.
His defensive pressure has increased significantly, almost tripling his average number of tackles per game to three.
Blessed with a huge 196cm, 101kg frame, Day also possesses an incredible vertical leap, making him a hard unit to stop in full flight.
Day kicked a career-best three goals against Port Adelaide in round nine last year, and the Power's backline coach Matthew Nicks said he would loom as a more influential player this time around.
"I hope he's not, but I think he has [become a greater threat]," Nicks said.
"Last time we came up against them the first five or 10 minutes of the game he was well and truly on top of us - looking back it was quite a scary time.
"It's amazing what a year of football under your belt can do…he's got a very good game, plus he's got that size and athleticism as well.
"I saw him playing college football back here in Adelaide a couple of years ago now, he's got the whole package.
"I have no doubt he's improved but I think a number of our guys are looking forward to the challenge."
Nicks said those around Day had also lifted their games in 2013, including small forward Brandon Matera and gifted on-baller Harley Bennell.
With another year of AFL football behind them, Nicks said the young Suns side had shown increased maturity in their opening three games of the season.
"[They've got a] lot more composure through the midfield especially. I know Gary (Ablett) is their go-to man and he's their standout, but Bennell's stepped up and his game is at another level now," Nicks said.
"Up forward they're a lot more competitive as far as doing their best to keep the ball in their forward line.
"Matera's in really good form; a sneaky small, gets out the back a fair bit, so we've done a lot of research on those two (Matera and Day)."
The Power have included former captain Dom Cassisi and comeback kid Robbie Gray in its side after the pair showed consistent form for West Adelaide in the SANFL.
Nicks said it was a credit to Gray to have returned to AFL football so quickly, given the severity of his injury suffered against Collingwood in round four last season.
The 25-year-old has booted five goals in his three SANFL performances this year.
"Robbie - what a fantastic effort to be back at this point in time considering the injury he had last year," he said.
"He's worked really hard off the track and it's a credit to him that he's back now and ready to go."
