The EuroCup is European basketball’s second-tier competition, behind the EuroLeague.
Besiktas took a 75-68 lead to the Copper Box after the first leg in Istanbul, meaning the Lions needed a victory margin of at least eight points to overturn the deficit.
The Lions led by 10 at half-time but Besiktas pulled that back to five points at the end of the third quarter, before Winterburn and Gustafson’s late heroics sent the home fans into bedlam.
And when the home side drew a foul with just three seconds remaining on the clock, Gustafson was cool enough to tuck away the two extra points to secure an 81-70 win on the night.
“It was incredible, we wanted to do it for each other. We’ve worked so incredibly hard this season, through the ups and downs with the investors and fighting for what we deserve, it’s been so special to come to this point and to celebrate with the team,” Gustafson said.
“We also wanted to do it for the other British teams – a lot of them were there watching us, so to be able to make history with them was very special.”
No British side had previously reached a European final and Wednesday’s EuroCup victory was the Lions’ 12th trophy since 777 took over the club in 2020.
In an era of almost total dominance, the club have won two Women’s British Basketball League (WBBL) Cups, four WBBL Trophies and three WBBL post-season play-off tournaments, and are on the hunt for a third WBBL Championship in a row.