"I can sit here and say I am confident our losing run will come to an end but I'm not," Coppell admitted.
"There are an awful lot of ifs - if we play well, if we do our jobs, if we don't relax at any time, if we take inspiration from the crowd.
"Key players are doing well against us at the moment - like (Steven) Gerrard and (Dirk) Kuyt last week. We have got to be more up to the challenge of individuals.
"We are not falsely positive. We are realistic - we have been playing good teams and we are playing one on Sunday.
"After 12 games we will have played the five top teams from last season. People were getting carried away after our start but after tomorrow we will have a more realistic appreciation of what the division has to offer. Then we can make our own judgement call."
Coppell expects Aaron Lennon and Robbie Keane to be Tottenham's biggest threats, as well as defender Michael Dawson, who scored against Chelsea.
"Lennon has certainly been the catalyst for them and Keane is a spark in that evasive role he has," he said.
"But you look at the whole of their side and again it is another team that has cost many millions to put together.
"And, as they showed against Chelsea, Dawson coming up for set-pieces could equally turn out to be a match-winner as Lennon or Keane."