Andriy Shevchenko has a virus and is in doubt for Ukraine's European Championship qualifier against Italy on Saturday.
Ukraine coach Oleh Blokhin said Shevchenko started to feel ill early Wednesday and was feverish with a temperature of 38.5 Celsius (101.3 Fahrenheit).
"I don't know whether he will recover or not (to play Italy)," Blokhin said.
Ukraine has three points in Group B, two ahead of Italy, but three behind leaders Scotland and France, reports AP.
"We should beat Italy," said Blokhin, adding that Ukraine is likely to "outplay Scotland, even if beaten by Italy."
Europe has recognised the need for negotiations with Russia to discuss the security system on the continent. Russian Foreign Minister Sergei Lavrov is going to Macedonia for meetings with colleagues within the OSCE