Neal Bunt and Zach Specht paced the host Eagles in scoring with 13 points apiece, while Jesse Kunzweiler added 12.
Jacob Fiedler led the Rockets with 27 points, followed by Cam Kuchel 15, and Alex Hanson 11. Hanson also led the winners in rebounds with six, and Fiedler grabbed five.
Dylan Speiler led the MMC boys on the boards with six rebounds, while Kunzweiler and Tyler Prunty snagged five each.
"Remsen-Union has a real good team with most of their lineup back from last year," said MMC coach Pat Bird. "Their edge in experience really showed when they pressed us. We turned the ball over way too many times to stay with a team of that caliber. Their outside shooting really stretched our defense out. R-U shot 51 percent from the floor, including eight three-pointers.
"Senior Jesse Kunzweiler had a nice all-around game for us. Many times we had five guys out on the floor for us who had not played together very much. They will only get better with each game."
The Eagles are playing without senior center John Hoefling, who broke his ankle in football and won't be back at full strength until Christmas.
The MMC teams host Le Mars Gehlen Friday night.