He started for England in midweek and feels he will be back in peak condition in a matter of weeks.
"I'm still searching for match fitness," the midfielder told Liverpool's official website.
"I still need more training and more matches under my belt.
"I got another 55 minutes or so for England, and I'm not feeling any injury, so I'm getting closer and need those minutes on the pitch.
"I feel as though my form will return in the next couple of weeks because I missed quite a bit of pre-season because of injury."