The good news for Schalke 04’s defenders as they prepare to face Chelsea in their opening Champions League Group G match on Wednesday is that striker Diego Costa is nursing a slight hamstring injury. The bad news is that even without being fully fit he has scored seven goals in his opening four matches for his new club since his £32 million ($52.03 million) transfer from Atletico Madrid.

Schalke will have plenty to fear if, as expected, he plays against them at Stamford Bridge. Those goals, which included a hat-trick in Chelsea’s 4-2 win over previously unbeaten Swansea City on Saturday, have helped preserve Chelsea’s perfect start to the season with a maximum 12 points, in contrast to Schalke who have one point after three winless games in the Bundesliga.

They know what to expect from Chelsea, too, after losing to them 3-0 both home and away in last season’s Champions League group stage, and on current early season form Chelsea look capable of beating them again by at least that margin.

After another impressive performance on Saturday, Costa, the first player since 1992 to score in his first four Premier League games, said despite his great start he had not yet settled down to life in London, but was settling in well at the club. “I have not yet been out in London, but I am trying to get to know it and bit by bit adapt to London,” the Brazil-born naturalised Spain international said.

Fabregas, who joined Chelsea from Barcelona in the summer, has also made an excellent start at Stamford Bridge, with assists in every game he has played so far.

While Chelsea are on the crest of a wave, Schalke, who finished third in the Bundesliga last season, are in a crisis. The royal blues were crushed 4-1 by Borussia Moenchengladbach on Saturday and are two off the bottom with just one point and a goal difference of minus four. That point came from a 1-1 draw with champions Bayern Munich.

City again for Bayern

Bayern have reached at least the semifinals in each of their last three Champions League appearances. With the 2014-15 final taking place in Berlin, the German powerhouse has added incentive to go for their second title in three years. Bayern kick off their campaign at home against familiar rivals Manchester City, as the sides meet for the third time in four seasons.

City ended the Bundesliga side’s competition record 10-game winning run when they met for their final group game last December, albeit with Bayern already through to the second round, and each has two wins and two losses from their previous meetings.

Bayern have made a solid start to the season despite a host of injuries and the loss of dependable midfielder Toni Kroos to Real Madrid. Experienced midfielder Xabi Alonso has also made an impact.

Former Borussia Dortmund striker Robert Lewandowski, one of Europe’s finest, has not quite yet settled in, though he has still managed one goal and set up three more in five appearances for his new side. Bayern also brought in Moroccan defender Mehdi Benatia, though it is youngsters Sebastian Rode and the 17-year-old Gianluca Gaudino who have impressed early in the season.

Midfielders Javi Martinez, Bastian Schweinsteiger and Thiago Alcantara are all out with knee injuries, but French winger Franck Ribery has returned and scored in Bayern’s 2-0 Bundesliga win over Stuttgart on Saturday.

Manchester City’s claims to become a major force in Europe will only stand up once the club goes deep in the Champions League. And manager Manuel Pellegrini believes this could be the season. “I think this team has a greater personality to try to win everywhere,” Pellegrini said ahead of City’s fourth straight season in the competition. City have only once progressed out of its group, and that was last season when they lost in the second round to Barcelona.

Messi-Neymar show

One of the most disappointing aspects of Barcelona’s failure to win major silverware last season was the lack of on-field chemistry between Lionel Messi and Neymar. Four-times World Player of the Year Messi and Brazil forward Neymar had injury troubles during 2013-14 but when they were fit, Barca fans, expecting the emergence of a lethal partnership scoring entertaining goals at will, were largely disappointed.

On the evidence of Saturday’s 2-0 La Liga win at home to Athletic Bilbao, however, this season may be a different story. Neymar came off the bench for the final half hour at the Nou Camp and netted a clinical double from a pair of superb Messi assists to preserve Barca’s perfect start to the season with three wins in three matches and no goals conceded.