The Costa Rican has endured a tough start to life in Premier League, having failed to find the net in any of his four matches.
However, the 26-year-old is adamant that he is not feeling any pressure and is confident that he will succeed in time.
"Everyone who knows me, knows that I want to play," said Ruiz. "I'm working hard in training to get my rhythm and hopefully I'll play some more in the next match.
"I'm not really feeling the pressure. I'm just going to do my best and show my quality. I hope people will see me at my best very soon.
"I feel fit. I know I can play 90 minutes in the Premier League. I played for 120 minutes against Chelseaand that has helped me. If I play more matches, I will get more confidence from that."
Ruiz was FC Twente's leading goalscorer last season.