Riki Wessels (50 off 33 balls) anchored the Sixers??? innings, while England???s Michael Lumb (27 off 20) was one of a number of other batsmen to chip in as the visitors posted 180-7 from their 20 overs.
Sixers then dislodged the Thunder???s star men, Jacques Kallis and Michael Hussey, early on and coped with some lower-order brutality from Aiden Blizzard (80 not out off 42 deliveries) to win their third straight match and leapfrog Adelaide Strikers at the top of the standings.
Lumb helped the Sixers begin their knock briskly, with the left-hander putting on 29 for the first wicket with Nic Maddinson (12) and a further 25 with Nottinghamshire colleague Wessels for the second.
The 34-year-old was dismissed towards the end of the sixth over when he misread a slow bouncer from Dirk Nannes and looped to Daniel Hughes at square leg after cracking four fours and a maximum.
However, Wessels pushed on and brought up his fifty with his second six of the match, thumping Nathan Hauritz back over his head, before top edging the spinner to Gurinder Sandhu at long off.
Wessels, the son of former Australia and South Africa batsman Kepler Wessels, was given support by Moises Henriques (18 off 16 balls) but the Sixers??? lower order also contributed.
Jordan Silk (23 off 19) and Ryan Carters (21 off 15) plundered 36 runs in partnership after Wessels departed with the score on 129 in the 14th over, before both batsmen were castled by Sandhu (2-28 from four overs) and the economical Pat Cummins (1-23 from four overs) snaffled Sean Abbott.
Brett Lee completely lost his radar at the start of Thunder???s reply, delivering five wides during an 11-ball opening over, while Mike Hussey took particular liking to Doug Bollinger, smashing the left-armer for successive boundaries in the third.
But Jacques Kallis was cleaned up by a gem of a delivery from Mitchell Starc before Hussey ??? who put on 160 with Kallis for the first wicket during Thunder???s 56-run win over Brisbane Heat last Sunday ??? picked out Maddinson as the men in green slipped to 38-2.
Abbott (2-28) then had Andrew McDonald (18) and??England ODI captain Eoin Morgan (6) pouched at fine leg and mid-off respectively as the required run rate rocketed up.
Blizzard picked up boundaries at will ??? six fours and four sixes ??? to secure his second Big Bash fifty and some powerful striking from Hughes (29 off 23) gave Thunder a modicum of hope.
But when the hosts could only collect four runs from the 18th over, bowled by Lee, their chances evaporated and they fell to a sixth straight reverse against their city rivals.