The England striker was substituted through injury shortly after cancelling-out Kevin Doyle's opening goal for the Royals at The Madejski on Tuesday night.
"It was a great game and we did a lot of good things which will stand us in good stead for the rest of the season," Coppell said after the 3-2 home win.
"Palace are a top outfit but we had a bit of good fortune out of Andy Johnson's misfortune.
"He is a real cutting edge for them but it shouldn't detract from our performance."