The 27-year-old limped off after 57 minutes of Scotland's 1-0 Euro 2016 qualifying victory over the Republic of Ireland last Friday and subsequently missed Tuesday's 3-1 friendly defeat to England.
Fletcher returned to his club to receive treatment and head coach Gus Poyet was fearful he could miss Saturday's Premier League clash at Leicester City.
However, the former Burnley and Wolves striker looks set to feature against Nigel Pearson's men at the King Power Stadium.
"Steven is OK - it was not nice at all watching the game and seeing Fletch coming off," Poyet told Sunderland's official website.
"Naturally as human beings we always think the worst, but we got in contact straight away with him and the Scottish medical staff, who were very good.
"They sent him back to us and we have done everything possible, so I will say I am 100 per cent sure he will play on Saturday."
Fletcher has scored four goals in nine Premier League appearances for Sunderland this season.
