Forwards Victor Moses, Kalu Uche and Emmanuel Emenike were all ruled out by injury before the tournament, while midfielder Ogenyi Onazi missed Monday's game with a knee problem.
Keshi hopes the Lazio player will be available for Thursday's encounter with Uruguay, which is likely to play a significant role in determining whether or not Nigeria progress from Group B.
"There are no (new) injuries to the players, because I've already lost four players," he said.
"With all this journey we've been having, arriving yesterday (Sunday) morning at four o'clock, I'm just happy there's no major problems concerning injuries."
Nigeria's preparations were disrupted by a dispute over bonus payments that meant the squad did not arrive until 36 hours before their first game.
Speaking ahead of the game, captain Vincent Enyeama had revealed that the disagreement remained unresolved, but Keshi said that was not the case.
"The issue of the bonuses has been settled. Nothing is holding us back anymore and all we need to do now is play football," he said.
Nnamdi Oduamadi, who scored a hat-trick for the African champions at Estadio Mineirao, said the players had put the dispute behind them.
"I'll say it's a big relief now, due to the stuff we had with the delay and missing the flights," said the 22-year-old forward, who spent the 2012-13 season on loan at Italian second-tier side Varese from AC Milan.
"This victory will give us a big morale. We'll talk in the group now, do everything the coach says, and we'll see what happens in the second game."
Nigeria's victory took them above Spain on goal difference at the top of Group B.