A look at what's happening in the Champions League on Wednesday:

GROUP A

European champion Bayern Munich can secure a place in the knockout rounds with another win over Salzburg. The Austrian team put up a fight against Bayern in their last game and took the early lead but was eventually overwhelmed 6-2. Bayern's main concern is its leaky defense. Bayern has conceded at least once in all of its last five games and dropped points in a 1-1 draw with Werder Bremen in the Bundesliga on Saturday. Atlético Madrid, which plays Lokomotiv Moscow, hasn't lost since the opening game against Bayern Munich in Germany. It has won five of its six games in all competitions since then, including against Barcelona in the Spanish league on Saturday. Diego Simeone again won't be able to count on striker Luis Suárez because of a positive coronavirus test. 

GROUP B

No one expected Real Madrid and Inter Milan to be struggling halfway through the group stage. Still, that's what has happened in a topsy-turvy group where neither Madrid nor Inter has beaten either of the supposed outsiders Borussia Mönchengladbach and Shakhtar Donetsk. That means Madrid's visit to Italy could leave one of the big two on the verge of elimination. "It's a final," Inter coach Antonio Conte said. "We have to win." Real Madrid will be without several players because of injuries, including Karim Benzema, Sergio Ramos and Federico Valverde. Out because of positive coronavirus tests are defender Militão and forward Luka Jovic. Gladbach hammered Shakhtar 6-0 away and can extend its lead in the group with another win over the Ukrainian club. 

GROUP C

One of four teams to have a 100% record after three group games, Manchester City needs just a point from its trip to Olympiakos to qualify for the round of 16 for an eighth straight season. City has netted three goals in each of its opening games, a far cry from its form in the Premier League where scoring has — somewhat unusually — been an issue for Pep Guardiola's team. Sergio Aguero could make his latest return from injury to strengthen City's attacking options after staying on the bench for the 2-0 loss to Tottenham on Saturday. Olympiakos starts the game in third place and three points behind Porto, which is away to a Marseille team that has yet to score a goal or collect a point this campaign. In fact, Marseille faces the humiliating prospect of setting a Champions League record of 13 straight defeats in the competition. Marseille shares the worst streak of 12 losses with Belgian club Anderlecht.

GROUP D

Liverpool can secure a spot in the knockout stage with two games to spare, and go a long way to clinching a first-place finish in the group, by beating Atalanta in their return match at Anfield. The English champions made it three wins from three by thrashing the Italian side 5-0 in their first meeting before the international break and are five points clear of both Atalanta and Ajax, who appear to be vying for the second spot. "It was a harsh result in the first leg but we start this game at 0-0," Atalanta coach Gian Piero Gasperini said. Mohamed Salah is available to play for Liverpool after returning to training following repeated negative tests for the coronavirus.