Jake Shields.

THE CANADIAN PRESS

NASHVILLE -- Middleweight champion Jake Shields spoiled Dan Henderson's debut in Strikeforce on Saturday night, controlling the former UFC and Pride star on the ground en route to a convincing decision.

The main event was followed by an impromptu brawl in the cage when rival fighter Jason (Mayhem) Miller entered the cage to challenge the champion.

The judges scored the main event 49-46, 49-45, 48-45 for Shields, who has won 14 straight since losing to Akira Kikuchi in December 2004.

Shields (25-4-1) survived a rocky start and then put his game plan into action, avoiding putting Henderson's power by putting him on his back and keeping him there.

The 39-year-old Henderson had no answers, despite being more than a 3-1 favourite.

"Henderson's a true legend, man, I'm glad to have beaten him," Shields said.

Miller, who had fought earlier in the evening, entered the cage during the post-fight interview on CBS to ask for a rematch. Shields beat Miller in November.

Suddenly punches were thrown and Miller found himself swarmed by a dozen people. When the dust settled, Shields apologized for getting involved saying his emotions were running high after the win.

Miller had stopped Tim Stout by TKO at 3:09 of the first round on the undercard.

Earlier, Muhammed (King Mo) Lawal upset light-heavyweight champion Gegard (The Dreamcatcher) Mousasi via a unanimous 49-45 decision at the Bridgestone Arena.

And lightweight champion Gilbert (El Nino) Melendez dominated in a five-round 50-45 decision over Japanese submission ace Shinya Aoki, who holds the Dream lightweight title.

Henderson dropped Shields with a right to the temple 20 seconds into the fight but the champion recovered and attempted a leg submission while his head cleared.

But the more powerful Henderson hurt Shields every time he connected and it was survival time for the champion who went down a second time. As the round ended, Henderson hurt Shields with knees in the clinch at the fence.

The 31-year-old Shields did far better in the second, passing Henderson's guard to take mount position after a scramble landed them on the ground. Henderson could not escape and took his lumps.

Henderson was on his back again in the third and Shields passed guard to get into mount again. The round ended with Shields attempting an armbar.

Shields kept looking to negate Henderson's power by taking him down. In the fourth, he mounted Henderson again.

The fifth started with Henderson swinging, only to be taken down again.

Henderson moved to Strikeforce after failing to come to terms with the UFC, for whom he last fought in July. Needing marquee names other than Russian heavyweight Fedor Emelianenko, the smaller Strikeforce was eager to sign Henderson and immediately matched him against Shields.

Henderson (25-8) has fought at both middleweight (185 pounds) and light-heavyweight (205) while Shields has campaigned at welterweight (170) and middleweight.

Henderson, a former two-time Olympic wrestler, was coming off a brutal knockout of Michael Bisping at UFC 100 last July.

The bull-like Lawal (7-0) used his wrestling skills to control the bout against a sluggish Mousasi, who was aggressive from the bottom but unable to get back up or show off his full bag of tricks.

Lawal scored two takedowns in the first round but was unable to inflict much damage on Mousasi, who was more than a 2-1 favourite. It was more of the same in the second although Mousasi started to scored with blows from the bottom. The round ended with Mousasi on Lawal's back, looking for a choke.

A tired-looking Lawal stayed on his feet for the first half of his third before taking down Mousasi again. The former all-American wrestler had a little more success scoring with his opponent on the ground this time.

The fifth round came with Mousasi (28-3-1) needing to make a statement. Instead Lawal, his left eye almost closed, put him on his back in 30 seconds.

Mousasi's troubles continued when he lost a point in the fifth round for an illegal upkick. Lawal ended the fight with an emphatic takedown -- his ninth of the fight.

The 24-year-old Mousasi, a native of Armenia who lives in the Netherlands, had won 15 straight since losing to Akihiro Gono in August 2006 in Pride.

The fight between Aoki and Melendez never heated up as Aoki was unable to get close enough to his opponent to use his submission skills. When the fight did hit the ground, Melendez controlled from on top, pushing him against the fence to take advantage of Aoki's unfamiliarity with the cage.

"I wish I could have pulled the trigger a little more but this guy's real dangerous." said Melendez, adding he reckoned he's now in the top three in the world at 155 pounds.

"I think I deserve a little bit of love now."

Melendez (18-2) took a finger in the eye in a first round, that saw the champion look to strike and stay out of range while Aoki tried to bring him down to the ground.

Aoki (23-5 with one no contest) was bloodied and a little frustrated by the end of the second. And there was more of the same in the third as Melendez punished him every time Aoki tried to take him down.

Melendez finished the fight with a flurry but was unable to put away Aoki, who failed on all 18 of his takedown attempts.

Aoki turned heads by breaking his opponent's arm last time out and then giving him the finger.