Alisher Usmanov said he has loaned the Russian Football Union (RFU) a further 300 million roubles (£3.5 million) to pay wages owed to national team coach Fabio Capello.
Arsenal shareholder Usmanov said in February that he had loaned the RFU 400 million roubles after the Russia boss went without pay for over six months.
The billionaire said he has now made a further loan to ensure Capello, who signed a lucrative contract extension in January 2014, receives the money he is owed.
"As a member of the Russia 2018 Local Organising Committee Supervisory Board, Usmanov decided to give financial help to the RFS to the tune of 300 million roubles," Usmanov's press service told the R-Sport news agency in quotes translated by Reuters.
"Ahead of the 2018 World Cup, the question regarding the head coach is of great importance for the national football team."
Capello has come under heavy pressure with Russia struggling to qualify for Euro 2016 and, although the RFU has said it is considering the Italian's position, it remains to be seen how it could afford to pay the reported €21m compensation required to release him from his contract.
Some Russia supporters started a crowdfunding bid earlier this month to raise the funds required to sack the former England boss.
Capello is under pressure to resign and he told reporters after the 1-0 defeat to Austria earlier this month: "I have no problem with speaking to my employers. If they have something to say to me, I am willing to listen.
"Before, there was an eight-month period when I worked for free. Now, the debt is two months. For me it's not a problem. The only problem is the work. If I was only interested in money, I would have asked FIFA to deal with the debt a long time ago, but I've done this out of respect for Russia and the RFU."
Asked how bad results would have to get before he would consider resigning, Capello said only: "Thank you for your question."
Russia's only two wins in Euro 2016 qualification group G so far have been a 4-0 home success over minnows Liechtenstein in September and a 3-0 victory by default against Montenegro in March.
UEFA awarded Russia the match after it had to be abandoned due to crowd trouble on 67 minutes, when the game was goalless.