ASK Riga won 83-69 in Latvia over Cajasol on Wednesday to take the upper hand in their EuroCup Qualifying Round 2 showdown.
The two sides will meet again next week with the aggregate score of the two games deciding which team will advance to the EuroCup Regular Season.
Bruno Sundov paced the Latvia giants with 21 points and eight rebounds while Ricardo Marsh poured in 19 and pulled down seven rebounds.
Corey Brewer also had nine points, seven rebounds and five assists for ASK Riga but the American was just three of 14 from the floor, including two of seven from long range.
The home side was on top at 70-65 when it broke away for a convincing triumph.
Sundov drilled a three-pointer and Uvis Helmanis caught a pass by Brewer and buried a jump shot for a 76-65 advantage.
Marsh and Sundov followed with baskets to open up a 14-point lead.
Sandis Valters extended the advantage to 16 with a pair of free throws before Andrea Pecile finished off the scoring with two from the stripe for Cajasol.
The Spanish outfit turned the ball over 22 times. They were led by Warren Carter's 15 points.
Ramunas Butautas (ASK Riga head coach):
"We didn't play badly but we had too many turnovers. We played good defense against their key players. We also dominated the boards, which certainly was important. 14 points is a good difference but still we will play the second game only to win!"
Ricardo Marsh (ASK Riga forward):
"It was a tough game for 40 minutes. Of course we are satisfied with the win but there is one more game left. It is always more difficult to play away."
Manal Comas (Cajasol head coach):
"ASK had a great game. Their team played on a high level and well organised. My team had a lot of problems early in the game. 14 points is a big difference but the winner will be decided after two games, so we will start to prepare for the second mach."
Warren Carter (Cajasol forward):
"ASK played the whole game with high intensity. We fought hard, but in the end it was a big difference. It will be a very tough game next week in Seville."