By ESPNSTAR.com staff
Real are currently top of Group D after picking up maximum points from their opening two games, while Real are two points behind them in second.
And while a point at the intimidating Signal Iduna Park is often seen as a good result for visiting sides, Essien, who is currently on loan from Chelsea, reveals his side will be going all out for the win.
"It will be a very difficult game," he told Marca. "However, we have to play to win against Dortmund.
"We will have to be on top of our game in order to bag the full three points."
The Ghana international was deployed in the unfamiliar role of left-back in Real's last game - a 2-0 win over Celta Vigo - but insists he is happy to play anywhere that coach Jose Mourinho asks him to.
"I have to admit that it's always a bit strange [to play at left-back]," Essien added. "Mourinho asked me to fill in there though, and I know I can play there.
"I am happy to play in whatever position Mourinho asks me to play. I have to work hard and make sacrifices for the team.
"I will continue to try and help the team to three important points."
Real are currently fourth in La Liga after picking up 14 points from their opening eight games, and are already eight behind leaders Barcelona.