There was a big jousting event held by the king. Sir Driant fought well, but was defeated. Sir Lamorak managed to best every other jouster at the event. 32 knights in a row were defeated by Sir Lamorak.
Then the king made a request to a knight known as Sir Tristram, to strike down Sir Lamoraks horse in a joust. Sir Tristram knew it would be shameful to take advantage of an opponents exhaustion, but he had to do as he was told. He defeated Lamorak, and felled his horse.
Rather than giving up however, Sir Lamorak demanded that Sir Tristram fight him on foot, but he refused the battle since he didn't want to bring more dishonor to himself. From that day on they were rivals ever since.
The King and Queen had set up a hunting area in which jousters could challenge each other. It was Sir Lamoraks lucky day to find such a Challenge, for he was always known to have pride in his swordsmanship. With him was a lesser known, but also quite talented knight by the name of Sir Driant. Sir Driant had jousted well, but his efforts were futile as he was defeated. Then Sir Lamorak mounted his steed, and began to joust. One after another he bested all the freelance-lances. Roughly 32 proud knights met the business end of his jousting abilities that day.
This put the King in a rather unsettling situation, as all the knights were defeated by this one man. Thus he made a request to one of the only two knights to have ever been considered stronger than Sir Lamorak. Sir Tristram was told by his king to strike down Sir Lamoraks steed. Sir Tristram knew that attacking a fellow knight while he was exhausted from battle went against the very code of honor that the knights of the round table stood for, but he could not deny his king. Against his own will, he challenged the weary Sir Lamorak to one last joust. Just as he was told to do, Sir Tristram made a fatal blow to Sir Lamoraks horse, and defeated Sir Lamorak. Sir Tristram felt the shame of his actions, as he had taken advantage of an opponents exhaustion, rather than fighting the opponent at their best, thus underminding the code which knighthood stood for.
As Sir Lamorak rose from the battle, he demanded that Sir Tristram battle him in an on foot sword fight, however Sir Tristram refused to fight him because he did not wish to bring more shame to his good name. From that day on Sir Lamorak and Sir Tristram were somewhat of rivals, even when they were shipwrecked on an island together. There are plenty of other stories about this man, but this one describes Sir Lamorak quite well.