Jupp Heynckes says Thiago Alcantara suffered a serious muscular injury during Bayern Munich's 2-1 win over Anderlecht in the Champions League on Wednesday, but Arjen Robben may have escaped more lightly.
Thiago was replaced just before half-time, with Javi Martinez coming on for the midfielder as Bayern shrugged off a slow start to pick up all three points.
Robben, meanwhile, was withdrawn three minutes into the second half.
Speaking after the match, Heynckes revealed the club faced an anxious wait to discover the severity of the Spain star's problem.
"Thiago suffered a serious muscular injury," he told Sky.
Of the veteran Dutchman, Heynckes added: "Robben said, he thinks it's not too bad. We have to wait for the diagnosis."
Heynckes was not completely satisfied with his side despite the victory, a result that keeps them second in Group B, three points behind Paris Saint-Germain, ahead of a clash with Unai Emery's side at the Allianz Arena next month.
Anderlecht had the better of the chances in the first half but the visitors won it after the break thanks to goals from Robert Lewandowski and Corentin Tolisso.
However, Heynckes felt Bayern were complacent against an Anderlecht side yet to pick up a point in the group stages.
"We played very badly in the first half and gave away two or three big chances," he added.
"Of course you need to be direct about that with the team. We went into the game thinking it would be an easy game because our opponents didn't have a point in the group. We gave the ball away far too often and they had too much space."
|Bolt not giving up on Manchester United dream|
|All Blacks must improve ´average´ set-piece, says Smith|
|Raiola hits back at Scholes following Pogba criticism|
|Indians top Red Sox in series opener|
|Struff stuns Cecchinato, Jarry reaches last 16|
|I´ll prove people wrong - Bolt completes first Mariners training session|
|Former champ Kvitova tops Radwanska, Pliskova ousted|
|Sad if it´s Filipe Luis´ last game for Atletico - Oblak|
|White Sox manager Rick Renteria hospitalised before game|
|Carragher: Van Dijk can become Liverpool legend|
|No timetable for Sale return from shoulder injury|
|This is a partnership - Rodgers on contract negotiations with Packers|
|Eagles QB Wentz unsure he´ll be cleared to play opener|
|Balotelli staying at Nice|
|It wasn´t a penalty, says Hodgson as Palace boss fumes at refereeing decisions|
|Salah can play much better - Klopp demands more from Liverpool star|
|Gasly to Red Bull: Vettel, Verstappen and the drivers who took their Toro Rosso chance|
|Klopp in the dark on Karius future amid links to Besiktas|
|Simeone pleased with draw after rigours of Super Cup|
|Captain Reus saves Dortmund in DFB-Pokal|
|I couldn´t care less - Klopp rejects title challenge talk|
|Ailing Bairstow keen to aid England´s unlikely victory bid at Trent Bridge|
|Redskins secure Peterson signing|
|Manchester City goalkeeper Bravo suffers ruptured Achilles|
|Crystal Palace 0 Liverpool 2: Milner and Mane secure victory at Selhurst Park|
|Whyte takes aim at ´coward´ Fury ahead of Wilder showdown|
|Jets delighted with Darnold, open to trading Bridgewater|
|Gasly to replace Ricciardo at Red Bull|
|Valencia 1 Atletico Madrid 1: Rodrigo strikes to deny Simeone´s side|
|Injured Halep withdraws from Connecticut Open|
|Cipriani fined £2,000 by Gloucester|
|Mourinho will be sacked before Christmas, says Sharpe|
|England face record chase after Kohli smashes India to huge lead|
|Ozil captaining Arsenal a miracle - Hoeness|
|Japan players apologise for ´thoughtless, careless´ actions at Asian Games|
|Henry wants Bordeaux job, Wenger confirms|
|Pogba too inconsistent and not a leader, claims Scholes|
|PCB chairman Sethi resigns in letter to Pakistan prime minister Imran Khan|
|US Open comes too soon for Tsonga|
|Unpredictable results making 2018 F1 season a classic - Wolff|
|Mendy restricts phone use on Guardiola advice|
|Modric brands Inter approach claim ´the greatest nonsense in history´|
|Runners and Ryders: Olesen leapfrogs Poulter into last Team Europe berth|
|Kenedy escapes further action over Camarasa kick|
|England´s Bairstow suffers ´small fracture´ to finger|
|Gonalons joins Sevilla on loan from Roma|
|Modric, Ronaldo and Salah final UEFA Player of the Year nominees|
|Tottenham to play opening Champions League home match at Wembley|
|Karius´ Champions League blunders did not lead to Alisson signing - Klopp|
|Leeds considered €20m Conte offer before turning to Bielsa|
|Modric, Rakitic lead new era for World Cup finalists Croatia|
|Storm´s Chambers banned for three weeks, Smith injury not serious|
|Porte to race Vuelta after recovering from Tour crash|
|The Career Golden Masters: A run-down of Djokovic´s magnificent record|
|Japan send home four basketball players from Asian Games amid prostitution scandal|
|Rugby tackle bags helping Liverpool´s Alisson with Premier League life|
|Federer raring to go at US Open after Djokovic defeat|
|Chelsea boss Sarri plans to give up smoking|
|Alonso´s Toyota team stripped of Silverstone victory|
|Ceballos: No issue with former Real Madrid boss Zidane|
|MLS Review: Martinez equals single-season goalscoring record|
|Astros avoid sweep with win over Athletics|
|Seppi advances, Paire exits Winston-Salem|
|Bale feeling good as Madrid eye sweep of trophies|
|You can´t leave a house three-quarters built – Neville urges United to back Mourinho|
|Dodgers slugger Machado leaves game after being struck by pitch|
|Harden says Carmelo will ´be a good fit´ for Rockets|
|Morata: I never considered Chelsea exit|
|Gavrilova kicks off title defence in New Haven|
|Lopetegui pleased with Bale and Real Madrid after LaLiga opener|