There have been several major chokes in tennis history. The most recent may well be the last Wimbledon final where Federer led 40-5 on his own serve with two match points to follow.
But there were other, some which come to mind,
1) 1948 Wimbledon final. Bromwich served at 5 games to 2 in the fifth set, and at 4-15, two match points, had two put-away volleys to win, dragged the first into the bottom of the net, let the other go by, which curled around and landed in. He lost the match.
2) 1957 White City Tournament of Champions semi-final. Gonzales led 5-1 (I believe), served for the match twice in the fifth set, was broken both times by Segura, who won the match and also the final against Sedgman.
3) 1953 Australian Hardcourt (clay) final. Rosewall held six match points, which he lost in a marathon five set match.
4) 1962 Roland Garros final. Emerson led Laver 4 games to 0 in the fourth set, but changed tactics and played less aggressively in an attempt to ensure victory, Laver then had a chance to play back into the match, and won.
This gives some idea. There are others I am sure.
But there were other, some which come to mind,
1) 1948 Wimbledon final. Bromwich served at 5 games to 2 in the fifth set, and at 4-15, two match points, had two put-away volleys to win, dragged the first into the bottom of the net, let the other go by, which curled around and landed in. He lost the match.
2) 1957 White City Tournament of Champions semi-final. Gonzales led 5-1 (I believe), served for the match twice in the fifth set, was broken both times by Segura, who won the match and also the final against Sedgman.
3) 1953 Australian Hardcourt (clay) final. Rosewall held six match points, which he lost in a marathon five set match.
4) 1962 Roland Garros final. Emerson led Laver 4 games to 0 in the fourth set, but changed tactics and played less aggressively in an attempt to ensure victory, Laver then had a chance to play back into the match, and won.
This gives some idea. There are others I am sure.