PER Diem: Jan. 13, 2009

Ron Artest and T-Mac will be stuck on the bench against the Lakers on Tuesday. Bill Baptist/NBAE/Getty Images

HOUSTON -- Welcome to The Grind.

This is the part of the season nobody likes to talk about. The part where your 10th man might play as big a role as your highest-paid player. The part where health is a relative term. The part where your depth is as likely to determine your fate as your stars.

When Houston takes on the Lakers on Tuesday in a showdown of two of the West's powerhouses, it will be no different from every other game I've seen this month -- at least one key player will be missing for both sides.

The Lakers might have only one healthy point guard, and as many as four rotation players scratched. Jordan Farmar and Luke Walton didn't make the trip, Sasha Vujacic is out thanks to back spasms and Lamar Odom remains questionable with a bone bruise in his right knee.

Los Angeles is the healthier of the two teams on Tuesday.

"We've been dealing with injuries since August," said Rafer Alston at Houston's shootaround Tuesday.

Houston will be without its two go-to wing scorers. Ron Artest was diagnosed with a moderate-to-severe bone bruise in his right ankle, the Rockets announced this morning, and will miss at least a week. Tracy McGrady, meanwhile, has been shelved for at least two weeks in order to regain his conditioning after several recent lackluster efforts.

Shane Battier, at least, will be back in the lineup to hound Kobe Bryant -- he forced him into a 11-for-33 nightmare the last time I saw these two teams meet, when the Rockets were winning their 22nd straight game last spring.

However, Battier noted this morning that he'll have to play more conservatively against Bryant this time because avoiding foul trouble is paramount given the absence of McGrady and Artest. And anyway, it's a mighty big task to ask him to shut down the league's leading scorer when he's just coming back after missing half a season.

And that gets to the bigger problem for the Rockets. While we've finally reached a point of the season where the teams they play have about as many injuries as they do, evening the scales on the personnel front, it still doesn't make up for all the lost time.

Because of all the injuries, the team has rarely practiced and has never had its full complement of players for a session. Before Monday the team hadn't had a full practice since Dec. 17, and in that one the Rockets still couldn't run full court because they had only nine players.

"In terms of identity and continuity [the Lakers] are further along than we are," Alston said. "I don't even know what practice feels like anymore."

So while the Rockets have stayed afloat, The Grind has swallowed up some of their mojo. And for Tuesday, The Grind is likely to leave us with some strange matchups.

Minus Artest and McGrady, Houston might rely heavily on a small backcourt of Aaron Brooks and Alston. Meanwhile, the Lakers won't have a true backup point guard and are likely to plug Bryant into that role. Meaning there could be a lot of size and quickness mismatches on the perimeter, and that Alston in particular might have to play a lot of minutes against Kobe.

"I know I can do the job on the perimeter," Alston said. "I think that's playing into my hands. But if he takes me on the post a double has to come right away."

It's not the way that either side drew it up in the fall when everybody had 12 healthy bodies. But at this point, right smack in the middle of The Grind, it's how wins and losses are decided.

John Hollinger writes for ESPN Insider. To e-mail him, click here.