Reading FC manager provided an injury update on first-choice goalkeeper Joel Pereira.
Selles opted to start 21-year-old keeper Coniah Boyce-Clarke after Pereira suffered an injury during the international break.
“Unfortunately Joel (Pereira) got injured himself when making a kick and twisted his ankle,” said Selles.
“Coniah (Boyce-Clarke) has been working really well and waiting for his opportunity, playing for us in the cups and with his national team. He is working well and I didn’t have any doubt.
“David (Button) has been injured until this week which doesn’t help the case. We have three good goalkeepers and they need to fight for the position.”
Boyce-Clarke had an afternoon to forget as his error saw Leyton Orient take a first-half lead and proved to be the winning goal as the Royals were beaten at home in the league for the first time since March.
Selles continued: “I don’t think it was a bad performance, it’s just that the position of goalkeeper you always magnify what happens.
“We should have defended that action much better. We need to be robust enough. We need to robust enough, we believe our ideas are correct and believe in these young boys.
“I’m disappointed with the performance we put in today. We didn’t get the high tempo we like to play and got caught in some situations that we should not.
“The game went according to the key moments which went for them. We were not at our best today.”
