Diouf has joined on a season-long loan from Manchester United and scored in Saturday's 1-1 friendly draw with Hearts.
Allardyce dismissed reports he could be about to make a move for Aston Villa midfielder Nigel Reo-Coker, but confirmed he is looking to bring in a new face at Ewood Park by next weekend.
Asked if he was interested in Reo-Coker, Allardyce told the Lancashire Telegraph: "No. Not at all. We are trying to bring someone in before Saturday though.
"We have one or two irons in the fire that have emerged over the last few days, which are exciting me a little bit more but (we are) still quite a way from securing any permanent signing."
Jason Roberts was not included in the Rovers squad for the trip to Scotland and Allardyce has invited bids for the striker.
"I think everyone knows by now we would listen to an offer for Jason," Allardyce said.
"I felt leaving him behind rather than playing him and risking an injury would be the best bet this weekend."