April did not go according to plan.

Rolles Gracie pulled out of his April 24 super fight with Ricardo Romero at Ring of Combat 17. The much-anticipated bout between Arunas Andriuskevicus and Alexander Gustafsson imploded at The Zone Fighting Championship “Dynamite” on April 25. Jan Blachowicz tore his rotator cuff and made the top European encounter and World Free Fight Challenge 8 main event with Igor Pokrajac impossible on April 18.

For every compelling bout that gets made, another gets scratched due to injury, contract dispute or a fighter pulling out for personal reasons. Let us hope the 10 must-see mixed martial arts tussles Sherdog.com has compiled for May have a higher probability of taking place, as fans are in for a real treat with each of them.

As always, this list does not focus only on the major bouts you already know to watch but rather on fights from all over the planet that are worth seeing.

10. Paul McVeigh vs. Marcelo Costa
Absolute Combat “Proving Ground,” May 23 -- Edinburgh, Scotland

McVeigh (14-5), the reigning Cage Warriors bantamweight champion, will return to action for the first time in more than 10 months when he takes on Costa (4-1). The 30-year-old Brazilian jiu-jitsu ace shocked the Swedish MMA community when he knocked out previously undefeated grappling wunderkind and reality show star Musse Hasselvall in October. Can McVeigh fend off the Brazilian’s challenge, or will he also fall prey to Costa’s dangerous game?

9. Antonio Mendes vs. Antwain Britt
Shine Fights “Genesis,” May 9 -- Celeste Center, Columbus, Ohio

Usually, it’s three strikes and you’re out. For Mendes (16-4), two defeats were enough to have him axed from the UFC roster. The versatile muay Thai fighter and former KSW tournament champion will resurface at the inaugural effort from Shine Fights, where he will take on “The Ultimate Fighter” season eight alum Britt (6-2). The heavy-handed 205-pounder, from Hampton Roads, Va., will look to rebound from a quick submission loss to Jamal Patterson that snapped his three-fight winning streak in February.

8. Hatsu Hioki vs. Ronnie Mann
Sengoku “Eighth Battle,” May 2 -- Yoyogi National Stadium, Tokyo

Somebody will have to lose in arguably the most exciting featherweight battle of the month. However, defeat is not something with which former TKO champion Hioki (18-3-2) or English whiz kid Mann are familiar; between them, they have lost just four out of a combined 41 fights. With big wins over Hideki Kadowaki, Jeff Curran and Rumina Sato, the 25-year-old Hioki entered the grand prix as the pre-tournament favorite. Due to his effective combination of wrestling and boxing, paired with a comprehensive arsenal of submissions, young Brit Mann (16-1-1) figures to provide a stern test.

7. Antonio Rogerio Nogueira vs. Dion Staring
Jungle Fight 13, May 9 -- Ginásio Paulo Sarasate, Fortaleza, Brazil

Though hard to believe, Nogueira (16-3) -- the twin brother of former Pride Fighting Championships and interim UFC heavyweight champion Antonio Rodrigo Nogueira -- has never competed in MMA in his native Brazil. That wrong will be righted on May 9, when “Minotoro” headlines the 13th edition of Jungle Fight against seasoned Dutch karateka Staring (15-5). The 30-year-old Staring trains at Golden Glory Deventer under Martijn de Jong and boasts 11 career knockouts on his resume.

6. Travis Lutter vs. Dean Lister
MFC 21 “Hard Knocks,” May 15 -- River Cree Resort and Casino, Enoch, Alberta

In a battle of two of the most advanced and seasoned American grapplers, “The Ultimate Fighter” season four winner Lutter (9-5) will take on 2003 Abu Dhabi Combat Club Submission Wrestling world champion Lister (11-6). Both fighters competed almost exclusively for the UFC in the past couple of years, with Lutter amassing a 2-4 record; Lister went 4-2.

5. Vladimir Matyushenko vs. Jason Lambert
Call to Arms 1, May 16 -- Citizens Business Bank Arena, Ontario, Calif.

Two longtime UFC veterans -- Belarusian wrestler Matyushenko (21-4) and Californian ground-and-pounder Lambert (23-9) -- will headline the premiere event for west coast promotion Call to Arms. With just three of their last 20 combined fights going the distance, Lambert and Matyushenko should provide fans with some fireworks. Matyushenko should have the edge as far as self confidence goes, as he will come into the fight with eight wins in his last nine bouts. Meanwhile, Lambert has not tasted victory in more than two years.

4. Takeshi Inoue vs. Rumina Sato
Shooto “The Final Tradition,” May 10 -- JCB Hall, Tokyo

Hardcore fans have demanded Sato (24-13-2) hang up his gloves for more than three years. A central figure in Japanese MMA in the 1990s, the much-beloved “Moon Wolf” enjoyed many memorable battles with great champions of the past, including John Lewis, Andre Pederneiras and Caol Uno. Regardless of the outcome of his bout with the Inoue (15-3) -- a man six years his junior -- there might be no better stage for Sato’s swan song.

3. Mamed Khalidov vs. Daniel Acacio
KSW 11, May 15 -- Torwar, Warsaw, Poland

Khalidov (16-3-1) was one of the fighters who suffered most from the demise of EliteXC. The 29-year-old completed just one fight under his contract with Pro Elite, leaving his home promotion KSW with the difficult task of finding worthy challengers for the “Cannibal.” It has done so in convincing fashion by bringing in dangerous Brazilian Acacio (17-7) for a catchweight bout at 195 pounds. Taking a page out of the UFC’s playbook, this move will allow Khalidov to make a test run and eventually ease down to middleweight.

2. Matt Hughes vs. Matt Serra
UFC 98 “Evans vs. Machida,” May 23 -- MGM Grand Garden Arena, Las Vegas

Three years ago, there would have been no argument regarding the hands-down favorite heading into this grudge match. Cutting a swath of destruction through a number of elite welterweights, Hughes (42-7) emerged as the most dominant 170-pound fighter in history. However, age and injuries have caught up to the 35-year-old wrestler, and, suddenly, Serra (9-5) appears to have a solid shot at making this a competitive bout.

1. Tatsuya Kawajiri vs. Gesias "JZ" Cavalcante
Dream 9, May 26 -- Yokohama Arena, Yokohama, Japan

Despite no title being on the line, this one will emerge as arguably the biggest lightweight fight of 2009. Former Shooto welterweight (154 pounds) champion Kawajiri (23-5-2) will look to continue building the momentum he created with an exciting fight and big knockout on New Year’s Eve. Meanwhile, two-time K-1 Hero’s tournament winner Cavalcante (14-2-1, 1 NC) blocks his path to a potential title shot. After sitting out more than a year with injuries -- his rematch with Joachim Hansen also fell through in December -- “JZ” wants to return with a vengeance.