The defending champions powered to victory after outscoring Sydney 28-11 in the second quarter at Melbourne Arena on Thursday night to take a 1-0 lead in their best-of-three semi-final series.

Casper Ware (22 points, seven assists) and DJ Kennedy (20 points, seven rebounds) led the way for United while Chris Goulding scored 11 of his 17 points in the decisive second quarter.

"Casper was really the one that got everybody going," Melbourne centre Josh Boone said after the point guard sparked his side from the opening moments.

"He hit those first couple of threes and that gets everybody going when he's playing like that."

Boone added 14 points and seven rebounds while Mitch McCarron was influential with 15 points, six rebounds and four steals.

Sydney kept in touch early but struggled to keep pace with Melbourne's high-powered offence, leaving Andrew Gaze and his coaching staff plenty of work to do before they host game two on Sunday.

"We are disappointed because we don't think that we played a brand of basketball that we've tried to build," Gaze said after the loss.

"You give a lot of credit to that because of the way United play - they pushed us out of our stuff offensively."

Brad Newley led Sydney's scoring with 17 while Jerome Randle and Kevin Lisch each added 13.

League MVP Andrew Bogut struggled to make an impact in his NBL play-off debut, finishing with seven points and seven rebounds.

United made a fast start by connecting on five of their first six three-pointers then blew the Kings away with a devastating second-quarter display to lead by 17 at halftime.

The Kings managed to slow the tempo in the third quarter but they were unable to reduce the deficit, Melbourne running away with the contest in the final term.

Ware was at his explosive best in the opening minutes, knocking down three long-range bombs as United raced out to a 15-8 advantage, but the efforts of Newley and Lisch helped Sydney close the quarter level at 24-all.

Goulding kick-started Melbourne's second-quarter charge with the opening five points while Boone slammed home twice as part of an 11-2 start.

The Kings tried to claw back the lead but Goulding nailed back-to-back triples before United closed the half on a 12-2 run for a 52-35 advantage at the main break.

The Kings made a 7-0 start to the third quarter as they tried to control the pace of the game but United attacked the basket to keep the score ticking over, building a match-winning 71-53 advantage heading into the final quarter.

Australian Associated Press