The Sixers appeared to be cruising to a third win in the last four starts on Saturday at John Cain Arena after holding a commanding 22-point lead with six minutes to play.

But the Phoenix almost pulled off the most unlikely of comebacks as they reeled off 17 points in a row to set up a grandstand finish.

It took some clutch play from Daniel Johnson and a three-pointer from Jack McVeigh to secure the result as Adelaide added South East Melbourne's scalp to recent wins over fellow contenders Illawarra and Perth.

"We didn't show up in Cairns (on Wednesday) and do the little things that we did tonight," coach Connor Henry said after the Sixers held on at the finish to improve their win-loss record to 10-14.

"They just kept grinding for the night and it results in really good play for us, some inner belief and we just want to keep trying to hang around pack going forward the rest of the season."

Johnson continued his recent stellar form with 22 points and eight rebounds with McVeigh's scoring punch off the bench (18 points) and a fine all-round display from Sunday Dech playing a crucial role in the win.

The Sixers are hopeful injured centre Isaac Humphries will make his return in next Saturday's must-win clash with Melbourne United.

Adelaide missed 11 of their first 12 shots but the Phoenix failed to capitalise as they scrapped their way to a 16-15 advantage after one quarter before falling behind 40-35 at halftime as Brandon Paul added eight points as part of Adelaide's 12-0 run in the second period.

The Phoenix continued to attack the paint in the third stanza but wayward outside shooting proved costly as they fell behind by 14 at the end of the quarter, Josh Giddey providing the spark for the Sixers despite battling with an ankle problem.

The match appeared over when Adelaide outscored the home side 12-4 to open the final quarter but Cam Gliddon and Izayah Le'afa fuelled a late Phoenix flurry with a barrage of three-pointers.

"We've done this a few times over the last two years really, where we've found ourselves in an almost impossible position and we find something, but we need to find it a lot earlier," coach Simon Mitchell said after the loss.

"We looked like a fatigued ball club tonight but I think we showed that it was mental fatigue because the energy was there for the last four minutes and that was disappointing."

Australian Associated Press