The Championship club have confirmed they are interested in the pair with Fortune the most likely to arrive at Keepmoat Stadium on loan.
Player agent Willie McKay, who has engineered the recent moves of El-Hadji Diouf, Pascal Chimbonda and Habib Beye to Doncaster, says that Fortune is a chance of joining prior to the loan deadline tomorrow.
"We're waiting for a player to come through training on Thursday, Shane Long, and if he's okay West Brom will allow Marco to come and join us. It would be until January 4," he said.
As for Zenden, Doncaster are aware he impressed whilst on loan at Celtic recently and have opened talks with him about a potential move.
"We've spoken to Bolo," McKay added. "He played for Celtic in a friendly against St Johnstone. I'm a Celtic fan myself and I was told he was outstanding. But he couldn't agree anything there and we've been in contact with him."