Zenit St Petersburg coach Luciano Spalletti has threatened to quit unless club bosses bring in more top class players just days after his team reached the Champions League last 16.
In an historic breakthrough for Russian football, for the first time ever both of the country's clubs - Zenit and CSKA Moscow - reached the knock-out round of Europe's most prestigious and lucrative club competition.
The success was hailed by Russia's media and football experts, but Italian Spalletti believes that to build on this success more top class players are needed.
"I really enjoy St Petersburg and I'd like to continue my work here," said Spalletti.
"But to continue our progress we need to strengthen with at least a pair of top-class players. We must go ahead otherwise I will have to resign.
"It's high time we purchased really classy footballers."
Zenit advanced after holding FC Porto to a goalless draw in Portugal on Tuesday.
Goalkeeper Vyacheslav Malafeyev, who lost his wife in a car crash earlier this year, was hailed as the hero of the match after an impressive set of saves in Porto.
CSKA defeated AC Milan 2-1 in Italy on Wednesday to join Zenit.
"Inter are a very strong team and it's extremely hard to take them on," CSKA coach Leonid Slutsky told www.gazeta.ru. "And it makes our win even more precious."
Slutsky praised Ivory Coast striker Seydou Doumbia who spearheaded the attack in the absence of his injured teammates, Czech Tomas Necid and Chilean Mark Gonzalez.
"I believed in our success up to the very end," he said.
"My team showed they also believed in me. Together we clinched the needed result. I'm really happy now. The result of the match with Inter has changed the outcome of our season to the better.
"We suffered misfortunes, injuries and unexpected losses throughout the entire season. But we kept on fighting and won a place in the Champions League play-offs.
"I think it's a good end to the long season."
The clubs are also leading the Russian league, which is now on a winter break, with Zenit top six points ahead of CSKA. The league restarts in March.