Manchester City lost a close 1-0 to Juventus on Wednesday in the Champions League and saw themselves overtaken by the Italians.
Juventus moves up to top spot in Group D with 11 points, City sits in second with nine points and has already secured a spot in the knockout stages. They also lost goalkeeper Joe Hart to injury in the second half.
“Both teams played well and we were unlucky to lose this game,” Pellegrini told mcfc.co.uk after the defeat. “Mandzukic finished well, but we had chances to at least draw – but missed them.
“It was important to score the first goal. We had the first chance to score with Fernandinho, but we didn’t take it.
“We tried to dominate the game and I am not unhappy the way we played because this is not an easy team or stadium to come to, but it is not the result we wanted.
“We have so many injuries it is difficult to continue the same pace, but we had the personality to do it and were maybe a bit unfortunate.
“I hope we beat Borussia and still finish top of the group because it is important to arrive in the knock out stages in first position.
“We have already seen a strong Barcelona. We hope our team will have more luck in the draw of the round of 16 this year but we will see.”
Hart left the game in the 81st minute with an injury, and Pellegrini was unsure how long the English international will be out.
“It is impossible to know how serious his injury is at this point,” Pellegrini said. “He has a problem with his hamstring and has had a problem in his back for the past week. We hope we don’t lose him, but for if for some reason he cannot play I have trust in Willy Caballero.