Why Leandro Trossard was missing from Brighton's matchday squad at Middlesbrough

Albion's Belgian international was an unused substitute in the midweek Premier League victory at Everton and at Middlesbrough, for the third round FA Cup tie, he was left out of the matchday squad altogether at the Riverside.

Trossard, who has seven goals and three assists from 17 outings this term, last played for Brighton in the 4-2 home loss against Arsenal and was withdrawn after 60 minutes following a poor display. De Zerbi believes the Belgian, who was excellent in the first half of the season, has been off-the-pace since returning from the World Cup, which has fuelled speculation he could be on the move this January.

Trossard, 28, is out of contract this summer but the club do have an option for a further year as Newcastle and Chelsea keep tabs on the situation. Speaking at the Brighton press conference ahead of the Middlesbrough match, De Zerbi said: "He’s one of the best players for us and one of the most important players for us. I’d like to always play with Leo in the first eleven, but it doesn’t depend only on me, it depends on Leo.

"I want players that work for the team on the pitch and Leandro knows very well my opinion, my idea. I’ve spoken a lot of times with him. I like him as a player, but I want more from him, because he can play better, he can work harder, he can run more on the pitch and I want players who give 100 per cent in every training session and every game. Without these characteristics, then they can’t play with me.”

De Zerbi added: “I don't know if its the World Cup. I have to wait and see and watch what my player does on the pitch. After a problem, I’m always open to understand and help my players in all situations, but on the pitch I want 100 per cent. I can’t understand 80 per cent or 90 per cent."