CSKA Moscow needed overtime to see-off Partizan 76-71 in Belgrade to go 2-0 in the Euroleague.
After leading 39-31 at half-time, the Russians let their guard down and let Partizan back into the game and with 6:00 left, Leo Westermann drained a three to give the Serbian champions a 55-53 lead to send the raucous Pionir Hall into a frenzy.
CSKA managed to re-group and tie the game at 62-62, sending it to overtime, despite losing all momentum, they had Sonny Weems to thank as he single-handedly gave the Russians new life in the extra period as he scored eight points to give his side a vital road win.
Weems led all scorers with 30 points.
"If Partizan won this game, I would have had a special reason to be the most happy man in the arena," Partizan coach Dusko Vujosevic said.
"An amazing game; both teams gave their best," CSKA Moscow coach Ettore Messina said. "Partizan played excellent all 45 minutes. I can not be happy after the 26 turnovers we had, but it is so important we switched the game. At the end of regulation we decided to defend instead of making a foul."
Bogdan Bogdanovic led Partizan with 16 points.
On a night full of games that went down to the wire, Panathinaikos edged Mapooro Cantu 78-76 in Athens to secure their first win in the regular season while leaving Cantu winless thus far.
Three-pointers from Andy Panko and Jonas Maciulis in the final four minutes sealed the win for the Greens despite a late surge from the Italians in a game that could have gone either way.
Sofoklis Schortsanitis led Panathinaikos with 19 points with Dimitris Diamantidis adding 12. Pietro Aradori and Manuchar Markoishvili both had 17 for Cantu.
Maccabi Electra also won at home by two points as they recovered from a poor first quarter to beat Montepaschi Siena 70-68 at the Nokia Arena.
Ricky Hickman led the way for the winners with 19 points as they overturned a 33-31 half-time deficit into a 53-52 third quarter lead.
Marcelus Kemp led Montepaschi Siena with 16 points.
Elan Chalon put in another impressive shift but unfortunately lost 74-71 to 2-0 Alba Berlin in the German capital.
Deon Thompson led all scorers for the Berliners with 24 points, shooting 12/14 from the field as Alba came from 11 points down with two minutes gone in the fourth to pull off a remarkable victory. A 21-2 run was the game-changer.
Besiktas have made a 2-0 start in their first Euroleague campaign after beating Brose Baskets 86-71 on the road in Bamberg.
Curtis Jerrells led all scorers for the Istanbul side with 27 points. Anton Gavel had 21 for Bamberg.
Barcelona won the highly intense defensive battle in Vilnius as they beat Lietuvos Rytas 67-49.
The Spanish champions pulled away in the third period to lead 47-36 and the Lithuanian side couldn't recover after that.
Euroleague's all-time leading scorer Juan Carlos Navarro led all scorers with 13 points in a game that most offensive-minded coaches would love to forget.
"In the first half we missed many shots, especially in the paint. In the second half we played better. The key to success was our defence and individual efforts," Barca coach Xavi Pascual said.