The California-based Strikeforce promotion returns to Showtime this Saturday night with two hungry welterweights vying for the vacant crown.

Strikeforce: Miami will also feature the undisputed queen of female MMA defending her title for the first time, in addition to the Strikeforce debuts of a Dutch powerhouse, a former Heisman Trophy winner and a professional wrestler.

Although the UFC remains the No. 1 organization in the sport, Strikeforce is rapidly gaining steam and popularity.

Strikeforce CEO Scott Coker offers a brand of MMA that delivers fights at the highest level with world-class caliber talent.  

Here's a breakdown of all the action on tap for Strikeforce: Miami this Saturday night on Showtime (Super Channel in Canada):

-Nick Diaz (20-7) vs. Marius Zaromskis (13-3)

Diaz, a UFC veteran with career wins over the likes of Gleison Tibau, Josh Neer, Robbie Lawler and Chris Lytle, is on the longest winning streak of his career.

Since losing to K.J. Noons because of a laceration at EliteXC: Renegade in November 2007, Diaz has been delivering sharp performances in the cage, effectively stopping all five of his opponents.

In his last two outings, Diaz defeated Scott Smith and Frank Shamrock to prove that he's a force to be reckoned with in two weight divisions. The six-footer Diaz outlanded Smith 207 strikes to 31 when they faced off last year.

The Cesar Gracie BJJ black belt has exhibited some of the craftiest submission skills in the game, in addition to world-class cardio. Diaz regularly competes in triathlons as part of his training.

A native of Stockton, Calif., Diaz has experience competing under just about every major promotional banner. At PRIDE 33 in February 2007, Diaz submitted top-ranked lightweight Takanori Gomi with a gogoplata. However, that win was later overturned when Diaz tested positive for marijuana.

With training partners like Gilbert Melendez and Jake Shields, the 26-year-old is rightfully exuding more confidence every time he steps into the cage.

In addition, Diaz's lethal hands have evolved to the point that he signed a boxing contract with Don Chagrin last August. Before making his mark in the sweet science, Diaz will first get a crack at becoming a welterweight champion in the sport that he has been mastering since 2001.

The Lithuanian-born Zaromskis captured the DREAM welterweight title in Japan last year after wins over Seichi Ikemoto, Japanese legend Hayato Sakurai and standout American wrestler Jason High.

A veteran of the British Cage Rage circuit, Zaromskis is a dangerous kickboxer with a base in wrestling.

Perhaps most impressive is the fact Zaromskis has knocked out his last three foes with sensational highlight reel head kicks, reminiscent of the Mirko "Cro Cop" era in PRIDE.

Both Diaz and Zaromskis are southpaws and it is likely they will engage in a standup battle, though Diaz will experience his greatest success on the mat.

Diaz must be considered the favourite based on his recent performances and marquee wins.

This fight will be the biggest challenge of Zaromskis' career, by far. Despite impressive showings overseas, Zaromskis still has a lot to prove whereas Diaz has already faced some of the best opposition in the sport.

The x-factor in this fight will be Zaromskis' striking. With 11 out of 13 wins by knockout, the London Shootfighters product has significant power.

On one hand, Diaz is more efficient and liberal with his striking as he likes to throw out a lot of jabs and straight punches before eventually wearing down his opponent.

Zaromskis, meanwhile, is more of a one-hit wonder. If Diaz keeps his hands low, Zaromskis could catch him early and put him to sleep.

As this bout enters the third, fourth and fifth rounds, the conditioning dynamo Diaz will wear Zaromskis down with a cavalcade of strikes before putting him away by either TKO or submission.

Verdict: Diaz via Submission, Round 4

-Cris "Cyborg" Santos (8-1) vs. Marloes Coenen (17-3)

Interestingly, Santos and Coenen were slated to face off at an XMMA event last year in Montreal, Canada. However, Santos could not compete as she was immediately signed to a multi-fight deal with Strikeforce.

The Brazilian export "Cyborg" is a wrecking machine in female mixed martial arts. A member of the Chute Boxe Academy, "Cyborg" has amassed wins over top female fighters Vanessa Porto, Shayna Baszler, Yoko Takahashi, Hitomi Akano and, most recently, Gina Carano.

Now a purple belt in Brazilian jiu-jitsu under Cristiano Marcello, the wife of fellow Strikeforce combatant Evangelista Santos is more than just a heavy hitting powerhouse.

Coenen, a product of Holland's world-class Golden Glory gym, is a solid submission grappler with dangerous striking. She avenged one of her three career losses by submitting Roxanne Modafferi last November.

Coenen should not be underestimated as she will present a tough test for Santos' first title defense. Coenen is more experienced, in addition to having a tremendous camp behind her.

However, the champion has brought a relentless pace in her last few bouts and her domination of Carano to claim the title last year was her most impressive showing to date. Although Coenen may be more technically proficient, Santos' sheer power is likely to be the deciding factor in this battle as she puts Coenen away via TKO in the second round.

Verdict: Santos via TKO, Round 2
 
-Robbie Lawler (16-5) vs. Melvin Manhoef (24-6-1)

In a real treat for fans, Strikeforce matchmakers have put together a middleweight slugfest between two of the division's toughest fighters.

Lawler, the last reigning EliteXC middleweight champion, is on the rebound trail after a submission loss to Jake Shields last June.

The HIT Squad member possesses victories over Scott Smith, Murilo Rua, Frank Trigg, Joey Villasenor, Falaniko Vitali, Chris Lytle and Tiki Ghosn. With experience competing for the UFC, IFL, EliteXC, PRIDE and King of the Cage, Lawler has banged with the best of them.

Nicknamed "Ruthless," Lawler is no stranger to high-level fights.

His submission wrestling base should be a decisive advantage against Manhoef.

But Lawler, a great boxer, also likes to trade fists. If Lawler fails to revert to his traditional wrestling and engages Manhoef in a slugfest, he is likely to go to sleep early.

Manhoef will be making his long awaited North American debut and hardcore fans can attest to the Dutchman being one of the most entertaining fighters out there.

The former Cage Rage light heavyweight champion is a Muay Thai specialist with world-class kickboxing experience competing for K-1.  In recent MMA contests, Manhoef has beaten Kazuo Misaki, Mark Hunt and Kazushi Sakuraba.

Lawler is a great striker himself, but Manhoef is that much better.

That being said, Lawler's coach Matt Hughes should be able to convince him to take Manhoef down where he is most vulnerable. If Lawler succeeds, he will capitalize on Manhoef's rudimentary ground game for the submission win.

Verdict: Lawler via Submission, Round 1

-Herschel Walker (0-0) vs. Greg Nagy (1-1)

In what may seem too ludicrous to be true, one of the NFL's all-time greats is taking a plunge into MMA at the age of 47.

However, this fight is hardly going to be the freak show many fans are expecting.

Even at 47, Walker is the epitome of a dedicated athlete. He's put in his MMA training for over two years and is serious about pursuing the sport.

Unlike Jose Canseco, who took a stab at MMA last year, Walker has been training extensively with the American Kickboxing Academy under Javier Mendez and Bob Cook.

The two-time NFL Pro Bowler has been able to benefit from world-class training partners such as Josh Koscheck, Jon Fitch, Cain Velasquez, Josh Thomson, Cung Le and Trevor Prangley.

Both Bobby Southworth and Luke Rockhold, Walker's teammates at A.K.A., are adamant he's the real deal.

Walker is attempting MMA because he legitimately wants to challenge himself, not because he needs a paycheck. He will be giving his full fight purse to charity.

At just 1-1, Nagy is also a relative novice to the sport. The 26-year-old Rage in the Cage veteran vows not to be a sacrificial lamb or stepping stone for Walker. Born in Hungary, Nagy now resides in the U.S. where he too has fully dedicated himself to the sport.

Given the nature of this fight, it is impossible to predict a winner. However, I will give Walker the benefit of the doubt and the slight edge.

Verdict: Walker via TKO, Round 1

-Bobby Lashley (4-0) vs. Wes Sims (22-12-1)

Rounding out the main card is another heavyweight showdown as Lashley makes his Strikeforce debut against Sims.

The pro wrestler Lashley trains at American Top Team where he has been building on his collegiate wrestling base.

Lashley has put his stint with TNA Wrestling on hold to focus his attention to MMA. Unbeaten in four pro bouts, Lashley is coming off the biggest win of his career -- a first-round stoppage of Bob Sapp last June.

Upon transitioning into MMA from sports entertainment, many pundits were already comparing Lashley to UFC heavyweight champion Brock Lesnar. While he may have the WWE experience and the same massive frame, his collegiate wrestling credentials are not quite the caliber of Lesnar's.

But with a full-time camp at ATT, Lashley could become a major heavyweight contender.

Sims, who has trained at Hammer House under Mark Coleman, is a UFC veteran whose career highlight was a win over Kimo Leopoldo in 2006.

Most recently, Sims was featured on The Ultimate Fighter where he was a teammate of Kevin "Kimbo Slice" Ferguson on Team Rampage. Sims was eliminated after getting choked out by Justin Wren in the first round.

Despite having the benefit of more experience, Sims has lost most of his high-profile bouts and this one should be no different. Sims has dropped bouts to Dan Severn, Frank Mir, Mike Kyle, Antoni Hardonk, Tim Sylvia, Travis Fulton and Canadian Steve Bosse.

Lashley should make an impact in his debut by taking Sims down and pounding him out in the opening stanza.

Verdict: Lashley via TKO, Round 1