compete against (someone or something)
To work or put forth effort against someone or something in an attempt to do something successfully. I'm probably competing against a hundred people for this job. Instead of competing against the loud music out here, let's go inside and talk.
compete against someone
to contend against someone; to play against someone in a game or contest. I don't see how I can compete against all of them. She refused to compete against her own brothers.
compete against something
to struggle against something; to seem to be in a contest with something. It was hard to be heard. I was competing against the noise of construction. Please stop talking. I do not wish to compete against the audience when I lecture.