The Sunrockers Shibuya played determined defense in the second half, holding the Levanga Hokkaido to 20 points over the final 20 minutes.
And that was enough for the Sunrockers to secure a 66-60 victory over the hosts and extended their winning streak to five games.
Shibuya (9-6) trailed 40-31 at halftime in Sapporo.
Sunrockers coach Geoffrey Katsuhisa's team faced a 50-42 deficit against its Easst Division rival entering the fourth quarter.
Shibuya forced 20 turnovers in the series finale, registering 11 steals in the process, with Kenta Hirose leading the way with four takeaways and Leo Vendrame making two.
Robert Sacre, a former Gonzaga University and NBA center, posted a double-double (13 points, 11 rebounds) for the Sunrockers. He also contributed three blocks and two steals. Tomoya Hasegawa knocked down 4 of 7 3-pointers to account for his 12 points, and frontcourt mate Josh Harrellson, also a former NBA post player, added seven points and 10 rebounds.
Yuki Mitsuhara poured in nine points for Shibuya and Vendrame and Hirose both had eight. Vendrame handed out a team-high six assists.
Kohei Sekino led the Levanga (8-7) with 16 points, making 4 of 5 shots from long range. Marc Trasolini had 13 points and Daisuke Noguchi finished with 10 points and two blocks.
The Sunrockers won Monday's series opener 77-67.
Shibuya converted 9 of 23 3s in the series-opening victory and the Levanga sank 5 of 21. Both teams made 19 2-point field goals and both attempted 50 shots.
Second-division update
In Tuesday's games, the Ehime Orange Vikings (11-4) defeated the Hiroshima Dragonflies 103-78 and the Fukushima Firebonds (11-4) topped the Aomori Wat's 105-86.
The Dragonflies fell to 7-8.
The Wat's, meanwhile, slipped to 2-13.
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