For the last two winners of the Premier League title, much has changed in just the first week of the season, and the mood surrounding Manchester City and Chelsea could alter yet further following their meeting at the Etihad Stadium on Sunday.

After winning the championship by 10 points last season, Chelsea came into the campaign as strong favorites to retain their crown. But murmurings of discontent over the summer bubbled over into more serious concerns in an opening 2-2 draw at home to Swansea City. Not only was there the dropping of points and the surprising vulnerability of their defense, but a sending off for goalkeeper Thibaut Courtois brought back into focus the decision to allow veteran backup Petr Cech to depart for Arsenal in the close season.

Manager Jose Mourinho had be strongly opposed to allowing a player he still rated extremely highly to join a team expected to be one of their major rivals for the title. And Cech’s departure was not the limit of Mourinho’s frustration in the summer transfer window. The Portuguese has also suggested on more than one occasion that he would have wanted the club to do more to improve last season’s title-winning squad, with their business having been limited to replacing backup players.

Perhaps that irritation is what led to Mourinho instigating an unsavory saga that has dominated Chelsea’s buildup to Sunday’s heavyweight clash in Manchester. Angry that his club’s medical staff went onto the pitch to treat the apparently injured Eden Hazard, meaning he had to depart the field and leave Chelsea down to nine men in the dying moments against Swansea, Mourinho launched a tirade against them on the sidelines. That criticism of Dr. Eva Carneiro and physio Jon Fearn continued after the final whistle both in front of the media and behind the scenes, culminating in the pair being removed from the bench for Sunday’s encounter.

Mourinho, who has been criticized by Football Medical Association, stood by his decision and his conduct in a press conference on Friday, but did state that the situation could change.

“Jon Fearn and Dr Eva Carneiro will not be on the bench but doesn’t mean that Sunday is the rest of our season, or the rest of our careers. They will not be on the bench on Sunday, that’s clear, it’s my decision, it’s my responsibility, but that doesn’t mean they cannot be in the future. If you want to speak to me about football, I’m here. If you want to ask about other things, I’m not here.”

The atmosphere couldn’t be much different surrounding Manchester City after the opening week of the campaign. The champions in 2012 and 2014 entered the season with plenty of doubts over their heads after a poor defense of their title last season and continued scrutiny about the future of manager Manuel Pellegrini. But, while those haven’t gone away, Pellegrini has been given a contract extension, and the team were mightily impressive in brushing West Brom aside 3-0 on Monday. To add to the feel-good vibe, two of the players whose performances dipped most alarmingly last season, Yaya Toure and captain Vincent Kompany, got on the scoresheet at the Hawthorns. On Sunday, Pellegrini, while again set to miss midfielders Fabian Delph and Fernando, suggested that last season’s top scorer Sergio Agüero would also be ready to be deployed from the start, after coming off the bench in the opening game.

The visit of Chelsea now affords City the opportunity to get an early five-point jump on the champions. Pellegrini, though, has stressed that it would be wrong to race to conclusions from such an early meeting between the two favorites to lift the trophy, although he would love to claim the three points.

“We are not thinking about the title in the second game, but we are thinking about to try to win out points here at home,” he said in his pre-match press conference. “Especially as we pay again the champions, the best team last season. Especially also against one of the teams that has a lot of chances to win the title. So to try and win the three points here at home is very important for our team.”

Kickoff time: 11 a.m. EDT

TV channel: NBCSN

Live stream: NBC Sports Live Extra