Barcelona and Napoli held up a banner saying "stop war" ahead of their Europa League play-off second leg tie on Thursday evening as football unites with Ukraine.
Both sides elected to hold up the sign ahead of the match at the Nou Camp to show their opposition to Russia's invasion of Ukraine.
Ukrainian playmaker Ruslan Malinovskyi unveiled a 'no war in Ukraine' undershirt after scoring a fine goal from outside the box for Atalanta in their 3-0 win over Olympiacos (5-1 on aggregate).
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Dinamo Zagreb supporters held up a banner which read "Support To The People Of Ukraine" during their Europa League match against Sevilla earlier on Thursday.
Bodo/Glimt fans held up Ukraine flags during their Europa Conference League win over Celtic.
The Polish, Swedish and Czech Republic FAs have released a joint statement saying that they will refuse to play the Russia national team on Russian soil in World Cup playoff matches in March.
Russia and Dynamo Moscow striker Fedor Smolov took to Instagram earlier on Thursday, writing "No to war!!!".
Everton defender Vitalii Mykolenko says "I ask the whole world to help my homeland" on Instagram.
UEFA are expected to move the Champions League final away from Saint Petersburg when its Executive Committee meet on Friday.
UEFA said in a statement on Thursday: "Following the evolution of the situation between Russia and Ukraine in the last 24 hours, the UEFA president has decided to call an extraordinary meeting of the executive committee for Friday 25 February at 1000 CET (0900 GMT), in order to evaluate the situation and take all necessary decisions."
British prime minister Boris Johnson said Russia should have "no chance of holding football tournaments" on Wednesday.
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