(Adds comments from Belgium coach Wilmots)
The central defender trained on his own for a second day on Friday while he received attention for the strain which he picked up late in Tuesday's 2-1 win over Algeria.
"I am fine thanks," he told a reporter when asked about his fitness before taking part in a group training session at the Maracana stadium in Rio de Janeiro on Saturday. "If everything goes well today, there shouldn't be any problems."
Belgium are top of Group H after the opening games which also saw Russia draw 1-1 with South Korea.
Belgium coach Marc Wilmots said Kompany was the only lingering injury doubt for Sunday's game.
Wilmots said he had been surprised that Russia only managed a draw against South Korea and said the team managed by Italian Fabio Capello had looked static for much of the game.
Wilmots said the Russians would be feeling more pressure than Belgium when they meet on Sunday in the Maracana.
"Our situation is good. We are not required to take the game to them. Algeria was a game that we had to win to get into a strong position. Now I think it's more Russia that has to take things in hand," Wilmots said.
"Will they do it or not? That's the question."
Wilmots is Belgium's all-time top scorer at the World Cup with five goals. The former midfielder's last strike came against Russia in a 3-2 win in 2002. (Writing by William Schomberg, Editing by Nigel Hunt)
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- Vincent Kompany