Hernandez, who can also operate as a winger, has admitted that he does not know if he will start for Leeds in their Championship game against Luton Town at Elland Road on Tuesday evening.
The Spaniard came on as a half-time substitute against Fulham at Elland Road at the weekend and was taken off in second minute of injury time after he played an important role in the win.
The 35-year-old has said that he is not fully fit due to a hamstring problem, and has admitted that he has been frustrated with his injury issue.
Hernandez told The Yorkshire Evening Post: “I feel a little frustrated in the last week because after the long break I wanted to play and help the team.
“When we played the last game [before the break] against Huddersfield I felt good, no problems and when we came back to train at Thorp Arch I felt good, ready to play.
“But just a week before the first game I had a muscle problem. I couldn’t play the first game. I have a problem in the hammy but nothing serious. It’s difficult to manage it because we have a lot of games but I can do this.”
The Spaniard added: “Obviously I am not 100 per cent but I feel good, I feel I can play and I can help the team.”
Against Fulham at the weekend, Hernandez played one key pass, had a pass accuracy of 71.4%, took 31 touches, attempted one dribble, made one interception, and put in one cross, according to WhoScored.
So far this season, the former Valencia and Swansea City star has made 25 starts and four substitute appearances in the Championship for Leeds, scoring six goals and providing six assists in the process, according to WhoScored.