The South Korean midfielder joined the Black Cats on a season-long loan over the summer.
However, the 24-year-old must miss this weekend's encounter at the Liberty Stadium due to ineligibility rules.
"I can't play against Swansea which is disappointing, but I hope the boys can play well," Ki told The Journal.
"Hopefully I will be back in the team for the Newcastle game. I feel much better now after playing a few games. I think I'll be stronger when we start again after the international games too."
Saturday will see new manager Gus Poyet take charge of Sunderland for the first time.