Gabriel Paulista says he has taken a gamble by joining Valencia from Arsenal, with coach Marcelino offering him no guarantees regarding playing time.
Valencia signed the Brazilian centre-back for an undisclosed fee last month with the 26-year-old signing a five-year contract.
Gabriel, who is reunited with Marcelino, his former Villarreal coach, at the Mestalla stadium, made a total of 64 appearances for Arsenal after joining in January 2015.
He told CV Radio: "Marcelino called me up and said he wanted me to come here but also stated that he was not going to gift me with a starting place, that playing depended on me. He said that I had to work and prove that I could play.
"That's what I'm here for. I'm going to fight to defend my spot."
Under Marcelino, Gabriel made 46 starts in all competitions for Villarreal in his one-and-a-half seasons with the club before his departure.
"I have a lot to thank Marcelino for because he helped me become a different player, a better player," Gabriel said. "When I arrived in Spain from Brazil, I suffered a lot because I struggled to adapt.
"My first training sessions were a complete disaster and I even thought that maybe I didn't know how to play football. I would go home every day very sad. But there he was, Marcelino, next to me in every training session, supporting me, saying 'Come on Gabi! Come on Gabi!'
"Even then, things didn't go as planned and I almost joined another club on loan.
"However, the injuries of Chechu Dorado and Mateo Mussachio allowed me to make my debut against Atletico Madrid. I played a good game and from then on, I was a regular for the coach."
Gabriel says he returns to Spain a stronger player following his time at Arsenal.
"My first months there [London] were complicated but a lot of people helped me, including the coach [Arsene Wenger]," he said. "With the help of my teammates I adapted and started to play. I gained a lot of experience in a very important league with a great club like Arsenal."
A medial knee ligament injury suffered earlier this year limited Gabriel to just 15 Premier League starts for Arsenal last season.
"It wasn't a serious one because I didn't break anything but I still had to be careful with the injury," he said. "Now I'm 100 percent ready to play if the coach wants me to."
After 12th-place finishes the past two seasons, Valencia are looking to return to the upper echelon of La Liga under Marcelino.
Valencia drew 2-2 with defending La Liga champions Real Madrid last time out to remain unbeaten this season.
"We have to fight to remain in the top positions and return to Europe," Gabriel said. "This club deserves a lot and all of the players have that thought in our minds. I'm confident we are going to have a great season."
Gabriel could make his Valencia debut in Saturday's home league game against Atletico Madrid.