Darren Ferguson labelled Doncaster Rovers' friendly with Chesterfield 'a waste of a Saturday afternoon' following Alfie May's sending off at the Proact.
Striker May was sent off for an apparent stamp on Spireites full back Bradley Barry, which came after he petulantly fouled Jordan Sinnott from behind.
It ensured one-way traffic in the hosts' favour and Ferguson admitted it was difficult to take anything positive from the final friendly of pre-season.
Ferguson was critical of May for his conduct and fears he could be suspended for the start of the season.
"All of a sudden we didn't get a foul on one side - which may or may not have been a foul," Ferguson said.
"It doesn't matter because the ill-discipline Alfie May has shown is nonsense. He would have been sent off in a normal game for the first tackle.
"If the referee reports it, as he's entitled to do, it's a straight red and he'll miss three games. It'll cost him two weeks wages - it's a waste of an afternoon for him.
"It then became a bit of a farce.
"It's ill-discipline that we can't afford to have because we have got five strikers on the books with Kiwomya being injured, he's going to miss the start of the season it's four.
"Now we're down to three.
"In many ways it makes my decision a bit easier but it's no good to anyone.
"It meant the game was not what we wanted it for."
Second half goals from Kristian Dennis, Delail Brewster, Gozie Ugwu and Reece Mitchell handed League Two side Chesterfield a deservedly comfortable win.
And as the game wore on, it became nothing but a fitness exercise for Rovers.
"It's difficult to analyse in that it became a bit of a farce in the second half," Ferguson said.
"I felt sorry for certain individuals that needed a game and for the fans because it was difficult for everyone in the second half.
"We were very young towards the end of the game.
"There were certain things I wasn't happy about before the sending off.
"I watched the first 25 minutes in the stand and I didn't think we played with enough urgency in the game.
"We just tried to change that a little bit.
"In the second half I started making so many changes.
"They did what I asked of them which is to make a training exercise and be disciplined and keep shape. Chesterfield were obviously going to have extra men in space.
"It's just a bit frustrating really and what can I take out of it? Not much.
"For Andy Williams, I felt for him. What was he going to get out it? Not very much,
"I've seen some things. Young boys got some time on the pitch and did well. I thought Tyler Garratt did very well.
"Joe Wright gave a good performance which I was pleased about. Craig Alcock got 90 minutes.
"I have to try to take the positives out of it but certainly, it's a wee bit of a waste of a Saturday afternoon to be honest.
"I don't think people should be taking too much from the result or the performance because it became a bit irrelevant with the red card and the substitutions I made."