Sandaza returned from an agonising spell on the sidelines against Annan Athletic at Ibrox on Tuesday night.
The 27-year-old Spanish striker has been out injured for nearly three months since fracturing his cheekbone against Motherwell in September.
He performed brightly before being replaced by Ross Perry after an hour following the red carding of Lee Wallace.
And he is hoping he can show why Gers boss McCoist pursued him last season and in the summer.
Sandaza said: "It hasn't been a great start for me as everyone else has played more than me.
"It is a long-term contract but hopefully soon, and after taking a step to come back, you will soon see the real me. I know it is not me yet.
"I am going to take this as a positive. I didn't expect to get on from the start. I expected Kal Naismith to play.
"I am happy to be back. It has been very tough being nearly three months out.
"This has been very important playing my first game since the injury, but the most important thing was to win three points.
"It was nice to get out in front of the crowd. It was an incredible feeling. I was nervous, but that is normal."