SEAN O'Driscoll believes Barnsley could provide the toughest test of a difficult week at Oakwell tomorrow.
The Nottingham Forest manager has seen his side beat Cardiff and claim a point at another of the promotion contenders, Blackpool, since last weekend.
But, while the Yorkshire side are struggling at the other end of the table, he warns they cannot be taken lightly.
"I have said it to the players – and I am not just saying this because it is easy to say now – but this could be the hardest of the three games," said O'Driscoll.
"Barnsley's organisation is robust, but they also have the fluidity of Blackpool.
"So they have a bit of Cardiff about them and a bit of Blackpool. This could prove to be the trickiest of the three.
"The other two were both tough games, definitely. But if we take this one lightly, then we will come undone."
Barnsley won 5-0 at Birmingham last month and 1-0 at Charlton last weekend.
"There is no difference between the qualities that keep you out of the relegation zone and the qualities that win you promotion," said O'Driscoll.
"That is what we would always tell the players at Doncaster.
"If you take Barnsley lightly, you can end up not just on the wrong end of a defeat, but a heavy defeat.
"Their away performance at Birmingham was proof of that. To beat somebody 5-0 away is some feat."
