Jon strained the medial collateral ligament (MCL) in his knee during Bon Jovi's Helsinki Olympic Stadium concert on June 17, as I mentioned in the last post.
This is the moment it happened, midway through Love's the Only Rule. Jon lets out a yell at about 0:28 and grabs his leg.
Jon gingerly makes his way out to the circle. He's in obvious discomfort at the end of Love's the Only Rule and the start of When We Were Beautiful.
This isn't the first time Jon's hurt himself this tour, having also torn his calf at the new Meadowlands Stadium in July 2010. To his credit, he didn't skip a beat then either.