In a fast-paced opening half, both teams executed well on offense and neither the Panthers nor the Rockets were able to pull away.
K-P was up 11-10 after the first quarter, with senior Colin Henrich contributing seven points.
Henrich continued to shoot the ball well and finished the first two stanzas with 17 points.
"He's a heck of a ball player, a tough matchup for anybody," R-U coach Steve Neuberger said of his opponents' playmaker.
The Rockets made some adjustments at the half and tried to limit Henrich in his offensive efforts.
The plan worked. The shots would not drop any more for Henrich.
"We did a nice job keeping it out of Henrich's hands as much as we could in the third and fourth quarter," Neuberger said.
R-U started to gain an edge when Tanner Hilbrands, who had struggled offensively in the first half, got things going for the Rockets.
"All of a sudden his shots started dropping and he was able to penetrate and get to the rim," Neuberger said.
Hilbrands made a three at the buzzer and the third quarter ended 40-34, Remsen-Union.
The Rockets added on to their lead in the final period and K-P did not have enough energy left for a comeback.
"Our defensive effort in the third and fourth quarter was what pushed us over the top tonight," Neuberger said.
Despite the loss, Panthers coach Adam Rapp was satisfied with his team's performance.
"The boys played hard," he said. "We have to learn to play a complete game. But there is a lot of improvement on our end and I like the direction we're going. We just got to keep working at it and keep on pressing forward. I'm proud of the boys tonight."
K-P's Henrich finished the night with 24 points, four assists, nine rebounds and three steals.
Hilbrands was the leading scorer for Remsen-Union with 20 points. Seniors Scott Schroeder and Andrew Hagert each had 10.
The loss puts K-P at an overall record of 6-9. They face West-Harrison in an away game today (Friday).
With the win, the Rockets sit at a 13-2 record.
They have won four straight games. R-U also plays today at Hinton.
"We're going to have to come ready to go and hopefully we can get another solid defensive effort like we did tonight," Neuberger said.