Having defeated Mt Lawley by 165 runs in round one, Joondalup set about dismantling Perth with a six-wicket win last Saturday.
The Centurions needed just 25.4 overs and two wickets to chase down the Demons’ 8-159 in the one-day match at Iluka Sports Complex.
Dutch international Mudassar Bukhari landed his first scalps for Joondalup, dismissing opener Jacob Snadden for five on his way to 2-28.
Paceman Josh Anderson led figures with 3-42.
Perth wicketkeeper Luke Jury top-scored for the visitors with an unbeaten 47.
Joondalup captain Michael Swart continued his solid start to the season with 64 to follow his 47 the previous week.
First drop Garrick Morgan top-scored with 68 not out.
The Centurions are home against the Hawks on Saturday.
In state T20 cricket, Joondalup opened the season with an exciting super-over win against Scarborough at Abbett Park.
With scores tied at 160, Bukhari took the ball for the first super-over, restricting the home side to just 2-1. Jaron Morgan hit the winning runs for the visitors.