The Portuguese remains cautious ahead of Tuesday night's game against the top side in Group E, especially with left-back Ashley Cole still unavailable with a rib injury
Chelsea manager Jose Mourinho is aiming for three points against Schalke 04 in the Champions League on Tuesday night - but is wary of the threat posed by the German side.
Schalke have won both their opening European fixtures this season, while Chelsea have won one and lost one, following a shock defeat to Basel in the opening round of matches.
Chelsea are 11/8 with BetVictor to beat Manchester City on Sunday
And Mourinho is expecting a tough tie against the side currently fifth in the Bundesliga, especially with left-back Ashley Cole still recovering from a rib injury.
"It's difficult for a team to be at maximum power, to play a match without somebody missing through injury or suspension," Mourinho told reporters. "They miss a couple of players but us too. Ashley Cole is an important player for us and is not playing. That's not a big deal. A team is a squad, not 11 players, and they have a squad with players to replace.
"What's the difference between [Jefferson] Farfan and [Christian] Clemens or [Max] Meyer, between [Marco] Hoger and [Roman] Neustadter? It's a good team, a good opponent, and hopefully we can be better than them.
"We play now two matches against the strongest opponent in the group and need points over these two matches. That's obvious. Tomorrow we have a game and we want to win and are going to try to win."
The former Real Madrid boss also announced that club captain John Terry would be starting but would not reveal the rest of his team, despite admitting he had already decided.
"I know but the players don't know," he said. "[With] only two days in between matches, I didn't train tactically for the game so the players don't know, so it's a principle I want always to keep.
"When they don't know I don't like to say. I have to make an option for tomorrow - I have to make a choice between David [Luiz] and Gary [Cahill].”
Mourinho also spoke of Cameroonian forward Samuel Eto'o, who netted his first Premier League goal for Chelsea against Cardiff City on Saturday.
"Cardiff was good for him, not just for the goal but for his contribution," he added. "His movement was very good; in the first half when Cardiff was compact and closed he was the one in attacking positions with better movement and participation.