Fighters you suspect have a GLASS JAW 100%

[WelshDevilRob]

Amir Khan for me, he gets sparked against anyone that lands flush on the chops.

Khan has a terrible chin. Can't think of anyone else at that level that qualifies.

[Rantcatrat]

David Haye.

Suspect chin. Granted I'm not totally sold that it should be referred to as a glass jaw yet, but it is suspect.

Ronald Hearns.

Enzo and Amir are proven to put the g in glass jaw. They shouldn't qualify as suspect.

What qualifies as a glass jaw anyway? A punch can knock you down or a punch can knock you out? Many fighters get tagged and go down but then go on to win fights. Does that mean they have suspect chins?