I was changing lanes as i was approaching a city street intersection at about 10 mph and began applying the brakes to stop. i noticed that i was having to push much harder on the brakes to slow the car and then noticed that the engine was racing at a high rpm. i was able to come to a stop and then put the transmission in neutral. at that point with my foot still on the brake and the transmission in neutral, the engine racing stopped and fell back to idle. i was then able to proceed as normal although i was somewhat shaken by the incident. nothing like this has occurred since. i did have the car evauated by my nissan dealership but nothing wrong was found.