The former Walsall, Bolton, Middlesbrough and England striker has struggled with fitness problems since signing for the club in the summer.
But Ricketts, 25, played well in Tuesday’s 1-1 draw at Reading and may feature again at Brighton today.
Blackwell said: "Michael put in a really good shift against Reading. He now knows he has to work much harder to make it at Leeds."
Leeds still have midfielder Jermaine Wright sidelined for up to a further two weeks with an Achilles tendon problem and full back Stephen Crainey is expected to miss out with groin trouble.
