Paul Warne said he had no choice but to task Will Vaulks with a "disgusting role" against Newcastle United.
The Rotherham United midfielder was told to man mark Jonjo Shelvey in Saturday's game at St James's Park.
And for 45 minutes, it worked.
Rotherham interim manager Warne had watched Shelvey set up all three goals in Newcastle's 3-1 FA Cup win over Birmingham City three days earlier.
Vaulks was asked to stop Shelvey, outstanding in the third-round replay, from dictating the Championship game.
But the 23-year-old – who followed Shelvey all over the pitch – could only watch in frustration as he delivered the free-kick which led to Newcastle's opening goal, scored by Daryl Murphy, in first-half injury time.
"We came and watched them play Birmingham," said Warne.
"We marked Shelvey out of the game (in the first half). I thought Will Vaulks, I mean it's a disgusting role to do, was outstanding. He followed him everywhere.
"You could see him getting frustrated. we limited him to very little chances first half. We had the best chance of the game. we had attempts on goal and corners.
"Obviously, I'm not going to come here and play three up front. I'm not that stupid. I thought the way we set up was working a treat and we were more than competitive first half. We went toe to toe with them.
"Unfortunately, which was unforgivable I think, the set piece ... we had more than enough time to get in position, and Shelvey was like a quarterback, which we knew, puts a good ball in behind.
"I think Fordy (Anthony Forde) should have got in quicker. I said it to his face. He's given me his all, so I'm not going to hammer him. He (Mruphy (has) turned and put it in just before half time. It was a psychological hit for the lads.
"They scored again and the game was away from us."
Matt Ritchie scored twice after the break, and Ayoze Perez also found the net.
The result saw Newcastle return to the top of the Championship.
Warne added: "I might be able to keep Shelvey quiet, but can I keep everyone else quiet?"