Sam Allardyce gave an injury update at his press conference ahead of his side's trip to Everton this weekend - with two of his best performers doubtful for the trip to Goodison Park.
Sakho has a back problem whilst Downing picked up a slight knee injury on international duty, after starting England's 3-1 win over Scotland at Celtic Park on Tuesday.
Sakho has made an impressive start to the season having scored six goals from eight Premier League appearance which has helped the side into contention for the Champions League places at this early stage of the season.
Allardyce told reporters: "You need to be very careful when you have a fixture list coming up like we have and you don't want to lose them for two or three weeks"
Allardyce added: "Andy is ready to start but I wouldn't say he is 100 per cent match fit. He's eager, as is Carlton Cole and we have [Enner] Valencia too so we have very good options."
As far as the start to the season is concerned, Allardyce isn't getting carried away with talk that his side could be in contention for European qualification come the end of the season.
He added: "I think it's too early to be thinking we're going to finish in the top five or six of the league. We're showing signs that we're capable but the consistency of your team has to be so good and this is the big test now - November and December."