The Rovers boss confirmed talks are on-going with a potential new addition before the deadline at 5pm on August 31.
McCann says a player could also be heading out of the club but insists any incomings do not rest on a departure.
"I'm not sure," McCann said on the chances of someone leaving the club.
"We may look to send someone out but if it doesn't happen, it's not a case that we have to.
Lakeside Doncaster: Emergency services launch search after man gets into difficulty in water
Lakeside Doncaster: Online tributes pour in for man who's body was found in South Yorkshire lake
Major Doncaster bridge will be closed for a whole month for essential maintenance
Lakeside Doncaster: Tragic end to huge rescue operation as body is found following search of lake
Scawthorpe fire: 'Avoid the area' warning as five crews tackle large wildfire during Doncaster heatwave
"We can bring one in without that happening.
"I'll have a good chat with my staff and make sure it's right that we do this.
"I think it's an important player if he comes.
"And I know the fans will be off their seats watching him."