Kristensen's two goals came within the space of three minutes off crosses from Tommy Oar.
German Thomas Broich added a third goal and Jamie Maclaren converted a late penalty to complete the rout for Roar to stay fourth on the standings equal on points with Melbourne Victory.
Sydney FC avoided their first defeat of the season despite playing with 10 men in a 1-1 draw with title rivals Melbourne City.
A penalty from Brazilian Bobo cancelled out Argentine Fernando Brandan's stunning first-half volley.
Bobo's penalty kept the Sky Blues undefeated in 10 weeks and six points clear ahead of Melbourne City.
Albanian Besart Berisha went to the top of the league's scoring charts with a hat-trick in Melbourne Victory's 3-0 win over Western Sydney.
Berisha's clinical finishing was the difference between the two sides and took his goal tally to eight to leapfrog previous leaders Irishman Andy Keogh and Uruguayan Bruno Fornaroli.
Perth Glory's title aspirations took a hit in a 2-1 home loss to strugglers Newcastle Jets.
The Jets were winless against Perth in their previous 14 encounters, but Andrew Hoole cancelled out Nebojsa Marinkovic's opener, before an own goal from Glory midfielder Milan Smiljanic in first-half stoppage time gifted Newcastle all three points.
Wellington Phoenix began the post-Ernie Merrick era with a sparkling 3-0 win over Central Coast in Hamilton.
Merrick resigned during the week with the Phoenix sitting bottom of the ladder with just two wins from eight starts.
But an early Kosta Barbarouses goal gave them the best possible start, while midfielder Vince Lia and Fijian striker Roy Krishna wrapped the game up with two superb second-half finishes.