The German defender, who is on loan from FC Cologne, missed the weekend's 0-0 draw with Norwich City because of illness with Bulgarian signing Manolev deputising at right-back.
But Riether says he welcomes the competition as it only makes Martin Jol's Fulham squad deeper for the season run-in.
"We have more than 20 players here who can play and who want to play," he told Fulham's official website.
"It's a long season and we have many games so it's important that if players are out injured or suspended, we have others who can fit in without a problem.
"For me, it's been a great time at Fulham so far. It was my first experience of another country and it was a big step for me to come to England. But I have to say Fulham is like a family and I like playing here. The fans are great, I like the stadium and it's been all good so far."