steal a march on

steal a march on  {v. phr.}

To get ahead of someone by doing a thing unnoticed; get an advantage over.

The army stole a march on the enemy by marching at night and attacking them in the morning.

Jack got the job by getting up earlier than Bill. He stole a march on him.

Compare: GET THE JUMP ON, GET THE BETTER OF, TAKE BY SURPRISE.