Jekabpils finished the first quarter with a 16-14 advantage and still led 21-19 after Jurijs Aleksejevs made a lay-up four minutes into the second quarter.
However, that is when the nightmarish 10-minute stretch began, with TU/Rock scoring 18 unanswered points until the halftime break to make it 37-21 and then adding 10 more after the interval.
Having fallen behind by 26 points, there was no way back for the Latvian team, who at one point were trailing by 36 points at 37-73.
Tanel Kurbas had a game-high 16 points for TU/Rock, while Augustas Peciukevicius and Janar Talts added 15 points apiece for the winners.
Troy Barnies was the top scorer for Jekabpils with 15 points, while Jurijs Aleksejevs was the only other player in double figures with 11.