Nowitzki connected on 5-of-7 3-point tries and grabbed seven rebounds as the Mavs started a three-game road trip with a seventh win in nine contests.
The 76ers, who had just eight players in uniform following a series of trade-deadline deals, were led by Thaddeus Young with 30 points and 13 rebounds.
Michael Carter-Williams matched Nowitzki's 25 points and Tony Wroten totaled 21 as Philadelphia dropped a ninth straight at home.
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