The Black Cats slumped to a 3-1 defeat to leave them second-bottom of the Championship.
Coleman has been linked with a move for Sheffield Wednesday's 6ft 6in Kosovo international Atdhe Nuhiu, along with his Owls team-mate Jordan Rhodes as he looks for a frontman to play alongside Joel Asoro and Josh Maja.
Coleman confirmed last night that he was set to sign a goalkeeper and Liverpool midfielder Ovie Ejaria, but said he was hoping for another experienced player to ensure a 'brutal' transfer window ends well.
He said: "We need one more, an experienced face with a bit of luck, but only time will tell on that one.
"It has been a brutal transfer window but if we get two or three in it will have been a good window for us.
"We’ve tried to do loan deals with a bit of money, whether or not we get them I don’t know.
“It’s obvious we need a bit physicality, you could see that tonight, even if Birmingham are one of the biggest teams in the league."