Motherwell manager Stuart McCall has reportedly cut short a holiday to open talks with Sheffield United.
Stuart Pearce does not think Reading goalkeeper Alex McCarthy needs to move to retain an England spot.
The 31-year-old trained with the club this week and his signing was confirmed ahead of Saturday's 4-0 win over Shrewsbury in the Capital One Cup at Elland Road.
Diouf has made over 300 appearances in English football after starting his career in France.
The forward spent nine years in the Barclays Premier League with Liverpool, Bolton, Sunderland, and Blackburn.
He also had a loan spell with Rangers before joining Doncaster in the npower Championship last season.
Diouf, who has twice been named African Footballer of the Year, made 23 appearances for Doncaster, but could not prevent the Yorkshire side from being relegated from the Championship.
Manager Neil Warnock said after the win over the Shrews: "He trained with us on Thursday and Friday and I will make a decision on him before next weekend because if I sign him (permanently) I will want him to be involved against Wolves.
"We have no money at the moment so he won't be retiring on the wages we can offer, but he is available on a Bosman transfer and he has genuine quality. He has always been a wild card and we have had our moments in the past, but I met him at a function a few weeks ago, I told him what I disliked about him and how I felt he could improve and it was a good conversation.
"I also spoke to a few people who know him well and they told me how good he is in the dressing room."