Arsenal face a crucial Champions League clash with Dinamo Zagreb on Wednesday but much of the pre-match talk has centred on a doping controversy from the reverse fixture.
Midfielder Arijan Ademi failed a drugs test following Dinamo's surprise 2-1 victory over Arsene Wenger's side on matchday one and has been banned for four years by UEFA, though he has always protested his innocence.
Wenger has called for more stringent testing within football and claims there is a prevalent assumption within the sport that doping is not a major problem.
However, Dinamo coach Zoran Mamic branded the decision to ban Ademi as "idiocy" as he confirmed an appeal would be taken to the Court of Arbitration for Sport.
"We are all shocked," Mamic said. "This is idiocy to punish a lad like this after he and experts have proven his supplement was polluted and accepted that he didn't know about it.
"Yes, he should have been more careful, the rules are strict, but to suspend him for four years is idiocy. And I wonder what would the fine be if it was some Arsenal, Manchester United, Bayern Munich or some other high-ranked club's player?"
Both sides must win to keep their hopes of progression alive, although victory will be immaterial if Bayern Munich and Olympiacos draw in Group F's other fixture, a result that would take the German and Greek sides through.
The Gunners' form has taken a dip in November, with their 5-1 thrashing by Bayern followed by a 1-1 draw in the derby with Tottenham and a 2-1 loss away to West Brom at the weekend.
Wenger has bemoaned Arsenal's recent injury problems and they suffered further blows at the weekend as Francis Coquelin was forced off with a knee injury before his replacement Mikel Arteta was substituted with a calf problem. Both will face tests to determine if they can face Dinamo.
Theo Walcott (calf), Alex Oxlade-Chamberlain (hamstring), Jack Wilshere (leg), Danny Welbeck and Tomas Rosicky (both knee) are all out, but Wenger stated on Friday that Aaron Ramsey should be fit to return following a hamstring issue.
Dinamo will be without the suspended Josip Pivaric as well as Ademi, while Domagoj Antolic and Gordon Schildenfeld (both thigh) are injured.
The Croatian champions have seen their season hit the stumbling blocks since Bayern ended their 45-game unbeaten run, having lost five of their last 10 in all competitions and keeping just one clean sheet in 12.
Dinamo have also failed to win any of their last 11 away Champions League matches, but the omens do not entirely favour an Arsenal side who are one defeat short of 50 in the competition: Wenger's men have not won back-to-back home games in the tournament since 2012, and only Maccabi Tel Aviv and BATE (both 11) have conceded more than Arsenal's 10 goals so far this term.