Tottenham Hotspur manager Ange Postecoglou singled out striker Timo Werner for criticism after substituting him at halftime in their Europa League 1-1 draw against Rangers on Thursday.
"He wasn't playing at anywhere near the level he should be," Postecoglou told reporters. "Timo's first-half performance was not acceptable to me.
"I told Timo that he's a German international, that I need everyone to be trying to give their best and this wasn't an acceptable example."
Postecoglou replaced Werner with Dejan Kulusevski, who ended up getting Spurs' equaliser after Hamza Igamane had scored for Rangers who looked the better side for most of the game at Ibrox Stadium.
Despite avoiding a third successive defeat following their weekend Premier League loss to Chelsea, the Australian manager was unhappy about his side's performance.
"I expect a lot more from the senior guys but we weren't anywhere near our best. It's fair to say that we're in a period of games that we're grinding through at the moment. But in the context of where we are in Europe and with our squad fairly depleted by injuries it was an important point."
Spurs are ninth in the Europa League as they look to finish in the top eight and go straight through to the knockout stages.
Postecoglou, who returned to familiar territory after coaching Rangers' fierce rivals Celtic for two years, praised his substitutes and the team's reaction in a hostile environment.
"Rangers are difficult to play against, especially here at Ibrox on European nights," he said. "With the nature of the competition and the atmosphere, not many teams can come here and win so you expect a tough game.
"When they score straight after halftime the energy levels obviously go up and it's going to be a tough one to claw back but I thought we worked our way back in well.
"I thought the substitutes made a difference and we scored a good goal, had other good moments and a great save by Fraser (Forster) at the end."