Georges St. Pierre vs. Nick Diaz And the Top 5 Fights That Didn't Happen In 2011

The UFC might end on a high note in 2011, but the year has been plagued by numerous injuries and other unusual events that have cancelled main events and superfights between the best of the best in the sport.

The most recent fight that was cancelled was a UFC 137 main event between UFC champion Georges St. Pierre and former Strikeforce champion Nick Diaz. Diaz pulled a no-show at two press conferences, which forced Dana White to pull him out of the fight and replace him with Carlos Condit.

Condit poses a big threat, but the anticipation behind GSP vs. Diaz was building in excitement over the past few weeks. It is definitely a letdown for the pound-for-pound star.

These are the five biggest and best fights that were scheduled for 2011, but were cancelled due to extenuating circumstances.

No. 5: Alistair Overeem vs. Antonio Silva

The Strikeforce heavyweight semifinals are scheduled to take place later this week, and the featured matchup between Antonio Silva and former Strikeforce heavyweight champion Alistair Overeem isn't taking place.

After Overeem got redemption against Fabricio Werdum, he pulled out of the tournament due to an injury and not having enough time to fully recover.

He signed with the UFC soon after and is now scheduled to face Brock Lesnar at UFC 140.

The one who gets hit hardest for the dropout is Silva, who is among the top 10 heavyweights in the world after his dominating victory over Fedor Emelianenko.

Many were predicting him to upset the former K1 kickboxing champion, but he will now have to settle for heavy underdog Daniel Cormier in a co-main event bout where the risk might not be worth the reward.

No. 4: Mauricio "Shogun" Rua vs. Rashad Evans

It has been a tough year for Rashad Evans, who lost his chance at regaining his UFC light heavyweight championship after pulling out of a scheduled UFC 128 bout versus Mauricio "Shogun" Rua.

He waited almost a year for a shot at it after defeating Quinton Jackson in May, 2010.

Jon Jones, who is Evans' training partner, stepped in and dominated the Brazilian muay thai expert to win the title at UFC 128.

Evans still hasn't had a second chance at regaining the title, but he did fight Tito Ortiz later in the year to keep himself in action.

No. 3: Georges St. Pierre vs. Nick Diaz

After pulling a no-show at two press conferences for UFC 137, Dana White reluctantly pulled Nick Diaz out of his scheduled title fight versus UFC Welterweight Champion Georges St. Pierre.

Diaz's trainers and mentors came out saying White did the right thing, but Diaz insists that he had attempted trying to get to the conference but missed his flight.

Missing a flight is one thing, but missing the fight entirely is another. Dana didn't want to take any chances and replaced him with Carlos Condit.

Diaz is currently riding a 10-fight win streak and is the former Strikeforce welterweight champion. He vacated the title and signed with the UFC after his latest victory over Paul Daley, who he knocked out in the first round.

St. Pierre is ranked No. 2 in the pound-for-pound rankings and is one of the most dominant fighters in the world. It was a challenge him and many fans were looking forward to for quite some time.

No. 2: Jon Jones vs. Rashad Evans

After winning the title from Mauricio "Shogun" Rua, UFC Light Heavyweight Champion Jon Jones and teammate Rashad Evans agreed to meet later in the year.

Jones would end up pulling out of the bout because of an injured hand and not being sure if it would require surgery.

It turns out the hand didn't require surgery, but Evans had already signed to fight Phil Davis at UFC 133.

Davis would also pull out of his fight with Evans, and was replaced with former UFC champion Tito Ortiz.

Evans got his victory over Ortiz, but everyone missed out on a fight that really mattered between Evans and Jones.

Jones is currently scheduled to face former Evans' opponent Quinton "Rampage" Jackson at UFC 135. Evans defeated Jackson last year and was expecting a title shot after the victory. He will have to wait till 2012 for his eventually shot at recapturing the title.

No. 1: Junior Dos Santos vs. Brock Lesnar

The most anticipated bout of the summer was a scheduled UFC 131 bout between former UFC heavyweight champion Brock Lesnar and dangerous striker Junior dos Santos.

After an entire season of the Ultimate Fighter was filmed and shown with the two opposing fighters, Lesnar was forced to pull out of the fight due to a second case of diverticulitis.

Both fighters missed out on the opportunity to showcase their skills and get a potential shot at Cain Velasquez. Well, at least Lesnar did.

The former WWE superstar was replaced with former title challenger Shane Carwin, who dos Santos dominated and beat over three rounds to earn a shot at Velasquez.

The "Brock Effect" played a big roll in PPV buys throughout the summer. Without his appearance on the PPV, fans were not as excited to purchase the summer shows, which feature some of the lowest buyrate numbers of the year.