Sergei himself is absent from national service due to picking up two bookings during qualifying and Andriy Shevchenko will have to do without his running mate against Poland on Saturday - a game Ukraine must win to guarantee a play-off tie against Germany or, at a stretch, England.
Should Sergei's countrymen fail to secure the guarantee, that is where his absent friend comes into play. Simon Davies and his Welsh team mates could do Sergei a big turn in Cardiff when Ukraine's play-off rivals Belarus come visiting.
"We could lose," pondered Sergei, horror struck at the thought. "But Wales are playing against Belarus and I wished Simon luck before he left. I told him 'good luck for your national team - you should beat Belarus!'.
"It will be difficult, because Ryan Giggs can't play in this game. I have played against the Welsh without Giggs and they are a good team, but with him they would be better."
Sergei's biggest frustration is the fact that he is unable to help his team in their hour of need, and his eyes will be fixed nervously on his television come Saturday afternoon.
"Of course it will be difficult, I love to play in my team, but I got two yellow cards.
"It is a bad time for me because I cannot play in the national team. We will be watching on television, I have some Ukraine channels at home. I don't think the Ukraine game will be shown in England.
"It is a very important game for us, if we win we can play the play-off game against Germany if England beat Greece."
By Richard Hubbard
Sergei Rebrov is hoping that an absent friend can assist Ukraine in their quest to qualify for the World Cup finals.