The 24-year-old joined City in a big-money move from Spanish side Valencia int he summer.
“I think that physically, I’m feeling better day by day,” he said on the club’s official website.
“Of course, I need to get a few more minutes on the pitch to get to optimum fitness levels and I’m sure that will happen with so many games coming up.
“I’ve been away a couple of times with the national team and that hasn’t helped.
“I’ve settled well in Manchester, but again, the international break probably came at a bad time for me.
“I love the club and fans already and I’m starting to learn English so I can communicate better with my team-mates, so as time goes on, things will get easier for me.
“I’ve been treated really well by everyone and the other players have been great, but I need to push on now.
“The Premier League is exactly the way I thought it would be with a high-tempo to the games. It’s very competitive and a challenge, but one I’m enjoying and ultimately hope to thrive in.”