However the Nipawin Hawks would not go away, and mounted a spirited comeback for a 4-3 win in overtime, and a 2-1 series lead.
Logan Casavant scored a pair of powerplay goals to tie things up, the latest coming with 3.9 seconds left in regulation, and with 1:02 left in the first overtime, Kenzie Arnold pounced on a turnover at his own blueline and scored on a breakaway to complete the comeback.
Kenzie's big brother Brandan also scored for the Hawks and finished with a goal and two assists, good for a league-leading 10-goals and 20-points through 12 games.
Declan Hobbs kicked out 28 of the 31 shots he faced in the victory.
Estevan's Bo Didur stopped 39/43 shots, while Zach Goberis added his 9th of the post-season, to go along with Guilderson's pair.
The Bruins look to get back on even terms, when they host Game 4 Wednesday at 7:30.