Tottenham Hotspur manager Mauricio Pochettino says his players should feel insulted and dishonoured if they lose their personal battles at free kicks and corners.
Spurs have conceded four goals from set pieces in their last three matches and are sure to be tested again by Brighton on Saturday given Seagulls centre-back Shane Duffy has already scored twice this season.
"It's an insult if someone beats you," said Pochettino. "If I am supposed to mark someone and he touches the ball then it's like a dishonour for me. That's how you need to feel. If you lose [that battle], all the tactics or organisation are gone.
"It's not a thing you can work on too much. You can work on your organisation. You can work on the line, if it's a wide free kick, higher or deeper. On the corner, you can use different positions to cover with different players because you know how the opponent works. "But in the end, it's up to them. It's the area of the game that you cannot do too much about from the outside."
Spurs started the season with three successive victories, including a 3-0 win at Old Trafford, but Pochettino warned his players not to get carried away with their own hype. They have since lost three games in a row, and the manager believes the lesson has been useful.
"I don't say I'm happy with this period but maybe I'm more close to being happy than angry, because sometimes you need a big hit to realise and wake up," he said. "We are good when we run more than the opponent. It happened in a similar way at Espanyol and Southampton. When we play against teams that have the same or maybe better quality than us, always we run between six and 10km more than the opponent.
"This season, it's not that we don't run -- we ran 2km more than Liverpool -- but we need more, because we have difficult qualities, because we have difficult skills and we need to be focused and run and work hard. For different reasons, we need to create double the opportunities or chances than another team to score.
"I don't say I'm happy. But it's good sometimes that you feel bad, and sometimes the critics arrive."
Pochettino is hampered by the fact that nine of his players played until the end of the World Cup and returned to Spurs just a few days before the Premier League kicked off. He has been rotating to protect those players from injury and left Toby Alderweireld and Kieran Trippier at home for this week's Champions League clash against Inter Milan.
"We provided more time [for Kieran] to recover after the international break to be sure he could play in a very good way against Liverpool," said Pochettino. "We didn't train too much because we prioritised the rest and recovery, and when he played and it was a tough game against Liverpool, 90 minutes, to play again three days afterwards against another big-level team, against a very good player in front [Ivan Perisic], I think it wasn't the best and the risk was massive.
"It's about not risking injury, and we've provided him with a very good week of training to be ready again.
"I go back to Manchester United. Remember in the second half, after 70 minutes, the two full-backs, Danny Rose and Kieran Trippier, asked to leave the pitch because they were tired, and they were ready again to play one week after.
"When you see all that happened it's an easy answer [to explain why they were left out]. But I don't want to explain in every single press conference my decisions and say 'no it's like this'."
Pochettino also does not want his players to use tiredness as an excuse for a lack of effort.
"We provided all the players 21 days off," he said. "It's more than some. I was talking with [Manchester City assistant manager Mikel] Arteta, because we wanted to be fair with everyone.
"City played one week before us in the Community Shield and all the players arrived one week before. They had only 15 days' holidays."