Step inside Cesar Gracie Jiu-Jitsu in Pleasant Hill, Calif., on any given day and, as the facility's name suggests, you'll hear the squeaky sounds of mats being rolled on as fighters fine-tune their submission holds and grappling defense.
Another, less familiar sound has infiltrated the gym in recent months as well -- the sound of boxers working over the mitts or a sparring partner.
Strikeforce welterweight champion Nick Diaz and lightweight titleholder Gilbert Melendez often produce the loudest pitter-patter at Cesar Gracie Jiu-Jitsu; both are renowned for their striking abilities and can be found sharpening their skills on any given day. But a surprising addition has been making noise in recent months, as well -- former Strikeforce middleweight and Elite XC welterweight champ Jake Shields, who -- up until recently -- had been considered more of a jiu-jitsu specialist than a stand-up striker.
Those who have been watching him closely say Shields has not only improved his striking skills, but his head and foot movement are now part of his defensive arsenal, as well.
"People are going to be surprised when they see how much better Jake looks standing," Melendez told ESPN.com. "He has put a lot of time and effort into picking up this aspect of his game."
Shields (26-4-1) has experienced much success in his career with limited stand-up techniques. His wrestling and jiu-jitsu are so advanced that it wasn't necessary to focus too much on boxing or kickboxing. But that changed when he joined the Zuffa ranks.
Receiving recognition as the best welterweight mixed martial artist on this planet has long been the source of Shields' motivation. But winning belts in Elite XC and Strikeforce don't get you top honors in this sport, something Shields knows very well. So, in 2010, he said "goodbye" to Strikeforce and its middleweight title belt, and "hello" to the UFC in hopes of landing a potential showdown against the world's top 170-pound fighter -- Georges St. Pierre.
"Fighting GSP is something I've wanted for years," Shields said. "I've been asking for it for about four years. I want to test myself against the best and I think [St. Pierre] certainly is the best."
But to be the best, Shields must defeat the best. And if he is to achieve his long-awaited goal Saturday night at UFC 129 in Toronto, Shields must put on the best performance of his professional MMA career.
After a less-than-impressive UFC debut in October against hard-hitting Martin Kampmann, whom Shields defeated by split decision, no stone in this latest camp went unturned. Shields ratcheted up the intensity, especially in his stand-up game -- where he is expected to be at a distinct disadvantage against St. Pierre.
The sparring sessions were brutal at times. Cesar Gracie's more skilled strikers like Diaz and Melendez never hesitated to exploit a hole in Shields' defense. If Shields failed to move his head, he ate a stiff jab. If he didn't move his feet, body shots served as constant reminders.
But on the occasion when a strike found an opening, Shields took it well.
"When the fight is standing, Jake has the best chin," Melendez said. "Nobody is going to hurt him standing."
Their reasoning for being tough on Shields was two-fold: They had bouts of their own to prepare for -- Diaz and Melendez successfully defended their belts April 9 in San Diego -- and they want Shields to be at his best against GSP.
Shields welcomed the tough love from his highly skilled teammates.
"They all have different things they offer, but still, I take advantage of what I can get, so it's been a tremendous help. I'm very glad we're all fighting at the same time; I have three top [fighters] helping me train right now."
Even with improved striking skills and more movement, it would be fatal for Shields to get into a striking contest with St. Pierre.
The UFC welterweight champ is among the most complete fighters in MMA. St. Pierre (21-2-0) is as comfortable standing as he is off his feet. Shields can't say the same. But while his improved head movement, footwork or jab might not stack up favorably against St. Pierre's in Toronto, it's a different ballgame when the fight goes to the mat.
"A guy who's got good submission holds is just as dangerous as a knockout puncher," St. Pierre said. "You can be winning the whole fight -- in the fifth round you're winning -- and at the last minute you commit a mistake and bang, you have to tap. It's just as bad as a knockout punch.
"Jake Shields has a weapon that's even more dangerous than a knockout punch. He always finds a way to bring the fight and his game where he is the strongest. That's why this fight is the most dangerous fight for me."
Shields might prove even more dangerous than St. Pierre expects if the challenger's stand-up comes close to equaling what it was during this training camp.
Franklin McNeil covers MMA and boxing for ESPN.com. He also appears regularly on "MMA Live," which airs on ESPN2. Follow him on Twitter at http://twitter.com/Franklin_McNeil.