The sight of Richards being carried off in the 1-0 win at the Reebok Stadium was a matter of concern for club manager Sven-Goran Eriksson and national team boss Steve McClaren.
Eriksson said: "He twisted his knee and will have a scan on Thursday. Before that is impossible to say if it is serious or not.
"But he is much better now than before. I think he was hurt trying to turn.
"He says he will be fine but let's wait and see what happens."
Richards must now be a doubt for England's crunch Euro 2008 qualifier against Croatia next month.