The 30-year-old was absent for Liverpool's 1-0 win over Reading on Saturday due to a minor hamstring injury that he picked up while on international duty with Spain.
"I'm getting better, little by little," Reina told the club's official website. "It wasn't worth taking any risks because you risk it getting worse. I'll be patient and get really good."
The Reds head into this Sunday's Merseyside derby in 12th place in the Premier League table, while Everton currently reside in fourth position.