A look at what's happening around the Champions League on Tuesday:

GROUP A

Bayern Munich coach Hansi Flick says Serge Gnabry could return to the starting lineup against Lokomotiv Moscow after an absence blamed on a false positive result in a coronavirus test. Gnabry sat out last week's 4-0 win over Atlético Madrid and the 5-0 demolition of Eintracht Frankfurt on Saturday. Bayern lost on its last Champions League visit to Russia in 2016 in a surprise 3-2 defeat to Rostov. Atlético tries to rebound from the loss to Bayern when it hosts Salzburg, with Luis Suárez coming off his fourth goal of the season at the weekend in the Spanish league. 

GROUP B

Real Madrid heads to Germany to play Borussia Mönchengladbach needing to kick-start its Champions League campaign following a 3-2 loss to Shakhtar Donetsk. The last time Madrid played Gladbach away, it lost 5-1 in 1985. Shakhtar hosts Inter Milan with more squad depth than for its surprise win over Madrid last week, after several players returned after isolation following a coronavirus outbreak in the squad. Inter has been relying heavily — some say too heavily — on goals from Romelu Lukaku. Brazilian forward Taison and midfielder Taras Stepanenko among those now available. Eden Hazard has recovered from injury and could make his season debut with Madrid.

GROUP C

Despite opening the group with a win over Porto last week, Manchester City plays at Marseille enduring a difficult start to the Premier League — failing to win three of its first five games. And City is without record scorer Sergio Aguero and fellow striker Gabriel Jesus. Fernandinho, Benjamin Mendy, Nathan Ake and Fernandinho are also sidelined. Despite his lack of confidence and goals, Dario Benedetto is expected to start at the Velodrome against City. Benedetto has not scored for the 1993 European Champions so far this season but coach Andre Villas-Boas has only a few options available for the No. 9 position. After its 1-0 loss at Olympiakos, Marseille is already under pressure as it plays its first home game in six years in Europe's top tournament. 

GROUP D

Liverpool is showing — for now — it can cope without Virgil van Dijk. The Premier League champions host Danish club Midtjylland after hard-fought victories against Ajax and Sheffield United last week without their central defender, who requires knee surgery and faces several months out. Midfielder Fabinho has been tasked with filling in for the Dutchman at the back alongside Joe Gomez. The game at Anfield sees the six-time European champions host a club who were only founded in 1999 and are making their first appearance in the Champions League. Atalanta, a surprise quarterfinalist last season, hosts Ajax, a surprise semifinalist two seasons ago. It's the first ever Champions League match in Bergamo for Atalanta, which played at the San Siro in Milan last season while its Gewiss Stadium was being renovated. But no fans will be allowed in.