In what Lakers coach Mike D’Antoni tabbed as “not a well guarded secret,” Shawne Williams will start at power forward in the team’s season opener tonight against the Clippers in a designated home game at Staples Center.

Williams had already disclosed after Monday’s practice, but D’Antoni didn’t bother to keep his lips sealed anymore following Tuesday’s morning shootaround. The Lakers will field the same starting lineup in the last two exhibition games, including Steve Nash (point guard), Steve Blake (shooting guard), Nick Young (small forward), Williams (power forward) and Pau Gasol (center).

Williams, who averaged 6.8 points and 4.4 rebounds through 18 minutes in the preseason, earned the nod partly because D’Antoni considers him an ideal “stretch 4” that will space the floor and add three-point shooting. Lakers forward Chris Kaman has practiced the past two days after staying sidelined for two games and three practices because of a stomach virus stemmed from the team’s recent trip to China.

Before Kaman’s ailments, he started in four of five preseason games posting 11.2 points on 51.5 percent shooting and 7.8 rebounds in 21.6 minutes per game. Once Kaman catches up on his conditioning, will he return to the starting lineup?

“I don’t envision anything,” D’Antoni said. “Those are hypotheticals. I envision that if somebody plays better or works better, then I will. We’ll see how it goes.”

Follow L.A. Daily News Lakers beat writer Mark Medina on Twitter. E-mail him at mark.medina@dailynews.com