Smith cleared the rope half-a-dozen times in Monday night's knock, taking him to the top of the tournament's six leaderboard with 24 - despite playing just four games this summer.
He brought up his half-century off just 22 deliveries - the quickest of his Twenty20 career.
Smith appeared on track to become the first player to notch three consecutive BBL centuries, before falling lbw to a Nathan Ellis full toss in the ninth over.
The 33-year-old - coming off an unbeaten 125 and 101 against the Sydney Thunder and Adelaide Strikers respectively - launched one Tim David delivery on to the Blundstone Arena roof.
Former Australia wicketkeeper Brad Haddin called for national selectors to ensure Smith was in their best T20 side.
Smith played just one match for Australia in the most recent T20 World Cup on home soil, with the hosts failing to get past the group stage in their title defence.
"I don't think you can not use someone in this sort of form. He's only 33. He's got another World Cup in him in the 20 over (format)," Haddin told FoxCricket during commentary.
Smith will play in week one of the BBL finals series, which begins on Friday, before heading to India for Australia's Test tour.
He had a life on 25 when Caleb Jewell parried a difficult chance over the boundary.
The Sixers lost momentum, and a clump of wickets, after Smith's departure before Ben Dwarshuis chipped in with an important 14-ball 30 late in the innings.
They have already secured second position on the ladder and will face first-placed Perth in 'the qualifier' final on Saturday night.
The seventh-placed Hurricanes are among five teams fighting for the remaining three spots in the top five.
A loss against the Sixers would mean the Hurricanes would need to beat the Brisbane Heat on Wednesday and have other results fall their way to make the finals.
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