Krisztian Nemeth had two chances for Kansas but failed to hit the target with either attempt, while Amadou Dia and Bernardo Anor had shots of their own saved in a dominant opening 25 minutes for Kansas.
Opara opened the scoring in the 50th minute from close range, but Kansas could only hold on to the lead for four minutes.
Sam was the man to level things up for the visitors, curling the ball into the net from long range to restore parity.
Dom Dwyer came close to scoring in the 58th minute, but his shot from 10 yards rolled past the left post. Dwyer then turned provider, heading the ball to Zusi, who shot over the bar from close range.
Kansas were forced to play the final 20 minutes with just 10 men as captain Matt Besler was sent off for a second bookable offence.
Red Bulls searched for a winner in the closing stages, and Sam came close to scoring a second, directing the ball past the far post after losing his marker inside the penalty area.
Matt Miazga threatened from the edge of the area but his shot was saved. Dwyer then nearly scored a late goal on the counter-attack, but his half-volley went inches past the post.