You are the internal candidate for an opening at your company.
But, the company is also interviewing a few candidates from the outside. How do you play it?
As an internal candidate you have many advantages. You already know the lay of the land and the people. You have detailed knowledge about the company, its client base, the market and the many challenges it faces. Similarly, the hiring decision makers already know you.
There are disadvantages as well. The hiring decision makers already know you, but they know you as the person in your current role. They might even know you too well and remember that time from three years ago when (fill in the blank). If they opened the job up to outside candidates versus just promoting you it means they're not completely sold yet.
The key is to get them to see you in a new light, to view you as the right person for this advanced role. Play to your strengths as the "no lose" option, someone who can hit the ground running. You already understand the culture, the market and the clients. You've demonstrated you are committed to the company, whereas someone from the outside might leave in a short period of time.
No need for the change candidate. Stick with the incumbent.