There is an old saying that goes: "Once is an accident, twice is a coincidence, and three times is a trend." With that said, BJ Penn goes into UFC 123 with Matt Hughes looking to avoid his third straight loss and a downward trend in his very storied and illustrious career.

To understand Penn's legacy we have to see how he got to this point. He started his professional career in the UFC lightweight division in 2001, when he was 22 years old. He won his first three fights and earned a shot at the lightweight championship.

He suffered his first loss as a professional in that title fight against Jens Pulver via decision. He was able to come back and win his next two fights and earn another title fight, this time against Caol Uno in the final round of a four man tournament. The fight was scored a draw and the title remained vacant.

Undeterred, Penn would move up in weight class to the welterweight division and would have arguably his finest moment as a professional MMA fighter. He went up against the seemingly indestructible Matt Hughes. It was a dominating performance from BJ Penn as he caught Hughes in a choke and won his first UFC championship.

Penn would leave UFC and move to K-1 where he would go 3-1, defeating Duane Ludwig, Rodrigo Gracie, and Renzo Gracie. His loss came against Lyoto Machida, who was fighting at 220 pounds against Penn's 191 pounds, via unanimous decision.

In 2006, Penn would return to UFC and the welterweight division. While he was gone, Matt Hughes won the welterweight championship back. So in Penn's first fight back he took on Georges St. Pierre in a number one contender match to determine who would get the next shot at Hughes. In a terrific fight, GSP got the split decision victory.

However, due to an injury GSP sustained in training, he was unable to compete with Hughes. Therefore, Penn was given the fight against Hughes. Penn started the fight dominating Hughes for the first two rounds. Near the end of the second round, Penn injured his ribs trying to take Hughes down and sustained a rib injury that would cost him the fight in the third round.

Penn would then move back to the lightweight division and win the lightweight championship in a fight against Joe Stevenson. The win made Penn one of only two men, the other being Randy Couture, to win titles in two different weight classes.

In 2009, Penn got a chance to hold both the welterweight and lightweight titles in a fight against GSP for the welterweight belt. Penn was dominated in that fight and lost via stoppage after Round 4.

Since that fight, Penn stuck strictly to lightweight fights and was successful in defending his title against Kenny Florian and Diego Sanchez.

In early 2010, Frankie Edgar earned the next shot at BJ Penn. In the fight, Edgar got a controversial victory via decision over Penn. The fight was incredibly close and most thought that Penn would get the decision or it would be a draw. Also, before the fight Penn had a serious sinus infection that really impacted his training and likely his performance.

An immediate rematch was given to Penn at UFC 118. The fight was very one-sided in favor of Edgar and he retained the title via unanimous decision.

That brings us to where we are right now, with UFC 123 on the horizon. BJ Penn will be looking to get back the momentum that he had before his fights with Frankie Edgar. He probably has the right opponent to help him get back what it is that he may have lost. Matt Hughes is a great fighter but he has never really been competition for Penn. He would have lost their second fight if not for that injury Penn sustained.

BJ Penn is still one of the best in the world at what he does. However, another loss would be severely devastating to Penn as a viable contender in the lightweight or welterweight division. He needs to win this fight a lot more than Matt Hughes needs to win this fight.