A wave of injuries will sideline key European football stars Tuesday when the UEFA Champions League resumes its new-look competition.

Kylian Mbappe’s sore hamstring is likely to sideline him beyond Wednesday when he was due to return to France with defending champions Real Madrid to face Lille.

Serious knee injuries mean Manchester City midfielder Rodri is out for the season and Barcelona goalkeeper Marc-Andre ter Stegen will miss at least most of it.

Inter Milan midfielder Nicolo Barella, who was a standout playing against Rodri on Sept. 18, will miss at least one Champions League game because of a thigh strain.

The injuries to four players who were involved in the European Championship into the knockout phase have sharpened the debate about player workload in a calendar made more congested by the bigger Champions League.

The extended program is what influential clubs all but forced UEFA to create and the 18 games this week, split between Tuesday and Wednesday, still leaves each of them with six more to play through January.

There were two repeats of past finals in the first week of games that relaunched the Champions League in a single-standings format. Man City and Inter drew 0-0 and Liverpool won 3-1 at AC Milan.

The next rematch comes Wednesday when Aston Villa host Bayern Munich, giants of the European Cup era that were shocked 1-0 in the 1982 final.

Villa Park will host their first game in the competition since March 1983 when the English side’s title defense was ended by Juventus.

Both eased to winning starts two weeks ago. Villa won 3-0 at Young Boys and Bayern’s nine goals against Dinamo Zagreb were a record for any team in the 33-season Champions League era.

Harry Kane scored four in Bayern’s 9-2 win and has a good record visiting Villa, with five goals there in five Premier League games for Tottenham. He faces a late check on an ankle injury.

Kane’s fast start to the season with 10 goals in seven games for Bayern has outpaced even Erling Haaland’s 10 in eight games for Man City.

Haaland was kept quiet by Inter for the second time in 16 months, a fact he was reminded of in a post-game talk with the Italian champion’s center back Francesco Acerbi, who smiled and held up two fingers.

Haaland should find it easier Tuesday in Slovakia when Man City faces Slovan Bratislava, which took the second biggest beating in the opening round, 5-1 at Celtic.

The pulsating atmosphere at Celtic Park for a rare European win by the Scottish champion stood out in an opening week where anticipation was not universal.

Attendance trends

Pundits including former Man City goalkeeper Peter Schmeichel noted a quietness about the stadium for the Inter game. The attendance was nearly 2,000 higher five days later when Man City met Arsenal in a tempestuous Premier League clash where title ambitions were already in play.

Milan-Liverpool was a heavyweight European fixture yet far from sold out, with fewer than 60,000 at San Siro. The crowd topped 70,000 at each of Milan’s first two Serie A home games this season and 66,000 on the equivalent Champions League opening night last season to see another English club, Newcastle.

Paris Saint-Germain drew at least 46,000 fans for each home game in Ligue 1 this season – and all three Champions League group-stage games last season – yet fewer than 40,000 were at Parc des Princes to see European debutant Girona two weeks ago.

Sporting Lisbon also had 40,000 fans for a Champions League opener against Lille and was 6,000 down on the crowd for a domestic league game against Porto.

The attendance and atmosphere trends will be watched as fans respond to the longer and more expensive program of four Champions League home games. The 36-team standings are set to be more dynamic for the final two rounds in January.

The raucous atmosphere should follow Celtic to Borussia Dortmund whose fans in the Yellow Wall tribune are among the noisiest in Europe.

Bundesliga champions Bayer Leverkusen host Milan after making a fast start in a 4-0 rout at Feyenoord. San Siro now reverts to Inter to host Red Star Belgrade.

Arsenal host PSG in a meeting of two teams chasing a trophy they never won. Each were a beaten finalist once. Also, Barcelona host Young Boys.

Even without Mbappe, Madrid should have too much for Lille playing in the stadium that hosted basketball group-stage games at the Paris Olympics.

Premier League leaders Liverpool host Bologna and Girona’s first European visitors to the Montilivi stadium are Feyenoord.

Dinamo Zagreb fired their coach, Sergej Jakirovic, after the drubbing at Bayern and brought back Nenad Bjelica for a second spell. He starts in the Champions League hosting Monaco.