Dolphins began the fourth period with a 59-48 lead, but Tarvas made it a one-possession game within a couple of minutes, with a pair of three-pointers sparking a 9-0 run.
The visitors were up 65-63 after a lay-up by Edgars Jeromanovs with four minutes left in the game, but Tarvas responded with four points in a row to take a 67-65 edge.
After both sides exchanged unsuccessful attempts, Dolphins had 14 seconds for the last possession, with the last shot trusted to Kendrick Brown.
Although it fell short, veteran big man Joakim Kjellbom was there to collect the offensive rebound and made the second-chance opportunity count, forcing the game into overtime.
Tarvas got off to the worst possible start of the extra period, with Edgars Jeromanovs executing a four-point play after being fouled on the three-point shot.
However, it didn’t rattle the Estonians, who gained a 78-75 edge after a pair of three-pointers by Kristo Saage and Juris Umbrasko.
Saage went on to increase the lead to 83-76 from the free-throw stripe after Adnan Chuck’s foul was deemed unsportsmanlike, while Edgars Jermonovs earned a technical foul on top of that to decide the outcome of the game.
Giedrius Gustas and Juris Umbrasko led the winners with 19 points each, as Rait Keerles added a double-double of 14 points and 12 rebounds.
For the losing side, Edgars Jeromanovs had 19 points and nine boards, with Adnan Chuck and Joakim Kjellbom collecting 15 points apiece.