Pedro has missed Chelsea's last three matches, while Costa sustained a rib injury during the Blues' League Cup defeat to Stoke City on Tuesday night.
However, while ruling out Branislav Ivanovic for a further week, Mourinho has claimed that the attacking duo could be involved at Stamford Bridge.
The 52-year-old told reporters: "Courtois and Ivanovic are out and Pedro and Diego we will wait. The others are fine.
"Pedro and Diego I am hopeful, if not I don't take them to the hotel. It is always difficult for me to find the percentage (how fit) it is more about the confidence of the players."
Chelsea go into the fixture in 15th position in the Premier League table.