Real Madrid has been keeping quiet about Cristiano Ronaldo's injury, and his presence in the second leg of the Champions League semifinals is likely to remain a mystery until just before next week's game against Manchester City.

Ronaldo underwent new tests on his injured hamstring Wednesday, but Real Madrid didn't reveal the extent of the problem or how long the Portugal forward will remain sidelined.

He was expected to play in Tuesday's first leg in Manchester, but watched the 0-0 draw from the bench after failing a physical just before the game.

There are widespread rumors about the injury, but the only clue since the game has come from a post on Ronaldo's Instagram account, which simply said, "Don't worry be happy," along with a photo of him smiling.