Mauricio Pochettino says Tottenham are still waiting to find out exactly how long England forward Harry Kane will be on the sidelines for.
The 23-year-old damaged his ankle ligaments towards the end of last Sunday's 1-0 win over Sunderland and Spurs are yet to learn how serious the damage is.
"We need to assess him every day," said Pochettino. "He's very positive.
"We need to do another scan and see how long.
"We cannot change the past. He got the injury against Sunderland last Sunday and we need to be positive.
"Harry is in a good mood. That is very important, to have all the energy and focus on trying to be available as soon as possible."
Meanwhile, Spurs will seek to keep their unbeaten start to the Premier League season going at Middlesbrough on Saturday.
Vincent Janssen scored his first goal for the club in the midweek EFL Cup defeat of Gillingham and is likely to deputise for Kane at the Riverside.
Pochettino does not want too much pressure placed on the Dutch international and said: "It's not only his responsibility [to replace Kane].
"It's a team responsibility and he needs to feel free to play and try to help the team.
"It's a big opportunity for him to show his real skill.
"He needs to enjoy the game. He has nothing to show, he just needs to play football.
"Always with a striker, they need to feel confidence and feel the net. It was a good opportunity for him to score his first official goal with us and that is always important.
"Tomorrow is a chance to maybe start and help the team."