Vedran Corluka was close to tears when he saw the tackle which left Eduardo da Silva with a double compound fracture of his left leg.
Arsenal's Croatia striker suffered the horrific injury after a challenge from Birmingham's Martin Taylor in the opening moments of the Premier League clash at St Andrews.
The full incident has been deemed too graphic for television, although limited replays are now being shown.
Arsenal confirmed on Sunday afternoon that the striker had been transferred from Birmingham's Selly Oak Hospital to an unnamed London hospital, where he will undergo further treatment.
And international team-mate Corluka was left distressed by Eduardo's plight, but believes Taylor had not intention to cause the injury.
The Manchester City full-back told Sky Sports News: "I was very disappointed and sad because Eduardo is my friend.
"When I saw that thing happen to him I wanted to cry because he's such a good guy and he didn't deserve that.
"I don't want to talk about that tackle. I think the player didn't want to do that, it just happened.
"I'm just sad because Eduardo didn't deserve that. The player made that tackle but I think he didn't want to do that, he was just unlucky on that tackle."
But Croatia captain Niko Kovac has blasted the "brutality" of the challenge.
Eduardo will definitely miss this summer's Euro 2008 finals and there are genuine fears his career could be threatened.
Kovac said: "I can't believe this happened. Also, I can't believe such brutality still exists in football.
"I don't even want to speculate about the time of his (Eduardo's) absence. Let's wait for the doctors to give their opinion."
Croatia manager Slaven Bilic said: "This is horrible. The fact he won't play at the Euros is less important - most important is that he recovers as soon as possible and resumes his footballing career.
"He is a great guy. Of course I will visit him very soon, trying to cheer him up."
And team doctor Zoran Bahtijarevic added: "Obviously, Eduardo won't be able to join us at the Euros, but that's least important now. As a great friend and sportsman, he will be missed until his return."