LONDON Chelsea manager Jose Mourinho, who said he made "11 mistakes" in his team selection after Chelsea lost to Newcastle United on Saturday, will not want to get it wrong again when Schalke 04 visit Stamford Bridge in the Champions League on Wednesday.
Chelsea won 3-0 at Schalke two weeks ago and are top of Group E by virtue of that win, with both teams on six points from three games.
Mourinho told reporters after Chelsea's 2-0 defeat at St James' Park that he was angry and worried by the performance that ended their run of six successive wins in all competitions.
"I made 11 mistakes, 11 mistakes. I should have picked another 11 and not this one," he said.
"When my team plays so badly, it's the feeling I have. I am angry because I don't understand why we lost," he said, adding that he was also "worried" about their away form which has produced one win in five away league games.
It would be a real upset if Chelsea failed to secure the win that would put them within touching distance of the Champions League knockout round and Mourinho plans to make changes to the team.
"I will be making a lot of changes for sure," he said before leaving St James' Park.
Schalke's players got their own wake-up call from club president Clemens Toennies last week and they responded by bouncing back from successive defeats to Chelsea and Borussia Dortmund in the Bundesliga to win 2-0 at Hertha Berlin on Saturday.
The players, who kept a clean sheet for the first time in five games, ran more than in any other league game and coach Jens Keller was pleased with their defending.
"What my team can take out of this game is that, when they are compact and defend set-pieces well, it's hard for anybody to score against us," he said.
Keller will have Kevin-Prince Boateng fit after the attacking midfielder returned to action on Saturday following a knee injury.
"We're in London and we know what quality they've got," Boateng said. "We're looking to get at least a point there. We're going to have to keep a clean sheet."
Boateng, who joined late in the transfer window from AC Milan, said he was gradually getting back to his top form.
"The knee is getting better by the game," he said. "You just need games to get to full fitness and sharpness."
Although Chelsea will start as the strong favorites, Schalke will certainly not be overawed.
They can take heart too from their last visit to London just over a year ago when they beat Arsenal 2-0 at the Emirates on their way to topping their Champions League group before going out in the last 16 to Galatasaray.