Borussia Dortmund goalkeeper Roman Burki believes his side's Champions League clash with Sporting CP on Tuesday will be crucial for their qualification hopes.

Dortmund are level on four points with Real Madrid at the top of Group F after two matches, but head to Portugal without a win from three games in all competitions following Friday's 1-1 Bundesliga draw at home to Hertha Berlin.

With Sporting CP just a point behind Dortmund and Madrid in the group, Burki feels the team must arrest their recent slide if they are to qualify for the next round.

"Of course this game is decisive in terms of how we finish in this group," he said. 

"We want to give a good account of ourselves, get back to a winning streak and we will do anything for that."

Dortmund general manager Michael Zorc agreed with Burki's assessment that Tuesday's game could be pivotal. 

"You do not have to be a wise man to say that the games against Sporting CP will have a decisive effect for the outcome of the group," he said.

"Which effect especially? Real Madrid will push through this group and you don't have to be a prophet to know that.

"In this … direct duel against Sporting CP you have to prove which team is the stronger one."