On a thrilling night of action in which Herschel Walker and Roger Gracie remained undefeated and Strikeforce middleweight champion Ronaldo "Jacare'' Souza outlasted Robbie Lawler to retain his 185-pound title, Nick Diaz closed the show in sensational fashion, turning back a determined bid by Evangelista Cyborg to win by second-round submission to successfully defend his Strikeforce welterweight championship before a pro-Diaz crowd of 9,048 at HP Pavilion live on Showtime.

The victory was the ninth in a row for Diaz (24-7, 1 NC), and the second defense of the 170-pound world title. Cyborg dropped to 18-14.

The main event was a slugfest, the southpaw Diaz landing solid punches with both hands while the gallant challenger did significant damage with an array of leg kicks and counter punches.

But shortly after Cyborg, the husband of Strikeforce women's middleweight (145 pounds) champion Cris Cyborg, scored an ill-advised takedown late in the second, Diaz finished him with an armbar at 4:50.

"He was eating a lot of punches,'' Diaz said. "For all the leg kicks he was throwing, I was landing more punches. He had taken too many punches and had to take me down. It was a mistake and I was able to finish him.

"(But) I respect the way he fights. He doesn't mess around. He came out here and fought me. He didn't play games."

In a bit of a pleasant surprise, for him, the talented Diaz was the clear choice of the crowd. The fans chanted "Dee-Az, Dee-Az'' several times throughout the action-packed fight.

"I think it's great to get a fight in front of a hometown crowd,'' Diaz acknowledged. "When I fought here before, I was fighting against San Jose when I fought Frank Shamrock. It's nice to have a home here now.''

Both Jacare, a slick submission specialist, and Lawler, the puncher, displayed their greatest strengths throughout their exciting fight. The hard-hitting Lawler almost knocked out the champion in the opening round. But Jacare survived and went on to retain his title for a first time.

Jacare captured the vacant Strikeforce middleweight crown on Aug. 21 with a unanimous decision over American military hero Tim Kennedy in Houston.

"I love my job,'' said Jacare, who forced Lawler to tap out at 2:00 of the third. "This was a great night. I don't know what's next but I'm ready to fight again and defend my belt.

"He fought with courage and a lot of guts. He got me hard in the first. I really felt it. But I used my heart to come back. He fought me off well in the second, but he was tired in the third.''

Said Lawler, who was coming off a devastating, 50-second, first-round knockout over Matt Lindland last Dec. 4 in St. Louis. "I just got tired. I wanted to keep it standing but I didn't have the energy to keep him off me''

Look for Walker, who seemingly never gets fatigued, even at age 48, to get back in the gym quickly after a dominant triumph over Carson.

"I'm happy I won and I'm happy I took it to the ground,'' Walker said. "My ground game has definitely improved. That's something we've been working on in the gym with all the guys since the last fight.

"I think I was a little bit too excited in the beginning. I let him kick...