Dier struggled during Monday’s 2-2 draw at Brentford and was partly at fault for the hosts’ second goal.
It was his 22nd start of the campaign for Spurs with the centre-back only once left out of the starting line-up by Conte this term.
While his impressive early-season form led to his England recall, Dier’s recent displays have become more inconsistent and despite retaining the backing of his manager, he could be rotated for the New Year’s Day clash.
Asked about Dier, Conte said: “I was a player, I know there are many reasons when you are struggling with something.
“You are not 100 per cent physically or mentally. You are a bit tired, but this is normal, especially if you want to play at a high level.
“Honestly, I’m not worried because I know Eric’s capacity and what Eric can do with us.
“It can be that you have a period where you have to recover mental or physical energy – but I am not worried.
“I have seen him with great focus and desire to come back”
🗣 Conte on the returning Cristian Romero... pic.twitter.com/Db8YVdQZNc
— Tottenham Hotspur (@SpursOfficial) December 30, 2022
“I have the other defenders that also give me the possibility to make rotations, if I see situations where I need to make rotations.”
With World Cup winner Cristian Romero expected to slot into the right side of Spurs’ back three, Conte could move Clement Lenglet into the middle and recall Ben Davies on the left if he decides to give Dier a rest.
Lenglet was one of several Tottenham players who remained at Hotspur Way during the World Cup.
Conte namechecked a handful of younger players on Friday that had caught his eye during the recent weeks in Japhet Tanganga, Pape Sarr, Oliver Skipp, Bryan Gil and Harvey White.
The aforementioned quintet could be part of the matchday squad on Sunday where Spurs will aim to begin 2023 with a victory.
When Conte was quizzed about his reflections on the past 12 months at Tottenham, he talked up their achievement of qualifying for the Champions League last season and conceded the race for the top four this time around could be even tougher.
He said: “For sure, I think to finish in the top four was a really big achievement for us. I think many, many people undervalued this achievement.
“Now arrives the difficulty for us. In this moment (Manchester) United, Chelsea and Liverpool are not in the top four. You are finding other teams. Arsenal are showing to be a really strong team.
I’m trying to push my players to understand that this season will much more difficult than last season
“Then there is City and Newcastle is another club that is growing year by year to become a title contender, a real danger for the Premier League title. For top four, (there are) other clubs also like Aston Villa.
“I think it will be very, very difficult for this reason. We have to know this.
“I’m trying to push my players to understand that this season will much more difficult than last season. That we have to try to continue to improve, to push ourselves.”