The Blues boss has confirmed that 27-year-old Lopez, who is a free agent having bought-out of his contract at Sevilla, has agreed terms on an initial short term deal and has been undergoing a medical with Blues but any decision on his signature has been put on hold.
"Jordi Lopez has been in, he's been doing a medical and we have to make sure everything is ok," McLeish has said.
"I don't like to say if anybody is going to sign until it's actually done."