Jurgen Klopp has said the note he handed to Daniel Sturridge in Liverpool's EFL Cup loss to Southampton was simply to explain the switch to a 3-5-2 formation.
Liverpool lost out 1-0 at St Mary's in Wednesday night's semifinal first leg, with Nathan Redmond scoring the only goal on a night when Southampton could have established a more substantial advantage.
Sturridge appeared nonplussed by a change of tactics in the second half, with other Liverpool players also bemused by Klopp's switch.
The former Borussia Dortmund manager said he had failed to get his message across to his players quickly enough.
"It was just a new system, however you want to call it, 3-5-2," Klopp said. "Two wingers, two strikers, that's all.
"No more information, but it was enough. I think we were a little bit too late when we gave him the paper when the game was already running on. That was our mistake. Things like this happen."
Klopp vowed that Liverpool would be much improved in the return leg at Anfield on Jan. 25.
"We will strike back, we will be a different team, different side -- everything will be different at Anfield," he said. "So for us it's still possible to go to Wembley and that's the target. That's the only comfort to take.
"Losing 1-0 is the third-best result you can get. I don't like it too much, but it's still possible. The performance doesn't feel too good, that's how it is, but for the final everything is open.
"At this moment there's two disappointed managers after the game, one because he lost, the other because he won 1-0 and has to go to Anfield, and that's how it is."
Information from the Press Association was used in this report.