The Netherlands international has not appeared for his team since their 4-0 defeat by Wolfsburg, in which he suffered a knee injury, but he is on schedule to complete his rehabilitation and return sometime in January.
“He's making good progress and will be able to help us again soon, hopefully in the first few games after the break,” Keller told Schalke’s official website.
“Klaas-Jan has been out for nearly seven months, so he won't be able to go from nought to 60 right away, of course. But I'm placing great hopes in him not just because of his qualities as a footballer.”
Keller believes Huntelaar’s return will be a huge boost for the entire squad, and, in particular, Adam Szalai, who has been standing in for the Dutchman.
“He's the type of person who can lead our young team and he'll be good for Adam Szalai as well. Adam had no experience of playing twice a week during his time at Mainz.
"With us, though, he's had to play a competitive fixture almost every three days and has never had time to take a breather.”