The 29-year old defender is on a season-long loan from German club Cologne and manager Jol has been so impressed that he is keen to keep him at Craven Cottage further than the end of the season.
"Sascha Riether has done a great job for us. He's enthusiastic, mobile and aggressive,” Jol said.
"I only wanted him on loan because you never know how they'll do.
"If he carries on like this we will make our mind up and try to extend it or buy him."