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Tim Duncan hurt his left leg, and everyone in San Antonio clutches their chest and Tony Parker and Manu Ginobili feel it in their back.

And none of that matters at the moment.

This is only a test of the Emergency Broadcast System. This -- Duncan going on the injured list, with the ability to be activated at any time since the Spurs didn't replace him on the active roster -- is for the moment, but the importance of Parker and Ginobili producing comes in The Moment.

The playoffs. San Antonio knows all about them, of course. Just not like this, without the shooting of Steve Kerr and the scoring of Stephen Jackson and the leadership of David Robinson. So, yeah, the Spurs are the defending champions, only not really. No less an interested party than coach Gregg Popovich will challenge anyone who dares suggest this group has earned anything yet.

Congratulations on that title. Whoever you are.

The differences in going for the repeat are many, but none is greater than the imperative that either Parker or Ginobili somehow, some way consistently produce on offense. It's not impossible -- it would not be a surprise if either had postseason hot streaks because they've had impressive runs before. But, in the only sure thing, both have been maddingly enigmatic in the same backcourt, and now only everything is riding on one of them emerging as a dependable second scoring threat before it's too late.

So forget that Duncan can't do it at all right now while on the injured list. What really matters is that he can't do it alone starting the third week of April, when the reigning MVP will need someone to ride shotgun. It'll have to be either Parker, the third-year point guard and walking stress test for Popovich, or Ginobili, the second-year shooting guard who's been moved to a reserve role and is undeniably a combined potential of special moments but just as much a broken power line, whipping every direction in the wind as sparks fly. They're both comforting and white-knuckle scary, depending on the day. OK, depending on the hour.

"Yeah," Ginobili said, not denying the special task of needing to carry more of the load. "The thing is, we are not very consistent players, so it's hard to be consistent. We have some good games and some not so good games."

Yeah. The veins in Pop's forehead have noticed.

The 2002-03 version of the Spurs won with defense and calm, but lost in the success of the grunt work and resiliancy was that the Spurs were good offensively, among the best shooting teams in the league. They just didn't take a lot of shots, thus finishing 12th in scoring. The current group, by contrast, is teetering around the late teens/early 20s in field-goal percentage, potentially testing the limits of how deep into the playoffs a team can go without any offense, even with the rebounding and defense that's the envy of most every opponent.

The contrast is that it comes alongside the most stable of players -- the smooth, efficient Duncan. His 23 points, despite dreadful 59.3-percent free-throw shooting, and 13 rebounds are a given, along with being an elite defensive forward. His pedestal, his team.

The problem comes when it looks like his team alone. Rasho Nesterovic, Robinson's replacement at center, has been better than the Spurs expected defensively but has been a disappointment on offense. Bruce Bowen led the league in 3-point percentage a season ago, but has returned to Earth. Hedo Turkoglu is challenging for a top-five finish in that category, exactly the kind of air cover for Duncan that San Antonio had hoped when it made the summertime trade, but he's also only averaging 8.5 points a game.

Parker and Ginobili are the only real hopes for a second breakout offensive weapon, to complement sure-thing Duncan. Either guard emerging as consistent scoring threats, as opposed to having the occasional bright-lights moment, retains a spot among the contenders for the defending champions. Neither developing the stability that has so far eluded them puts intense pressure on the defense throughout the playoffs, much more than existed on that end last season, and allows opponents to be concerned with stopping just one Spur.

"They've got to come out every night and give us something in the way of scoring," Popovich said.

Parker has been a lightning bolt since the day he arrived, a steal at No. 28 overall in the 2001 draft with great speed and toughness, only more frustrating than anything because of inconsistent play. He was the X-factor even last season when Robinson was still a fixture. Another late hot streak like that and the Spurs surge all over again.

Ginobili is in his first full season, after his 2002-03 debut was marred at the start by a badly sprained ankle. The recovery was so impressive that coaches voted him second-team All-Rookie, convincing the Spurs not to sweat letting Jackson leave as a free agent. It was also supposed to be the first step in Ginobili developing as a major offensive weapon, with 3-point range and slashing skills to get to the basket, but he's already been sent to the bench. Part of that switch was so San Antonio could massage Turkoglu's fragile confidence, with a payoff since he has been made the starting shooting guard, but the move was also made to make sure there's some scoring among the second unit.

No second scorer means no second consecutive title. At least the thought is consistent.

Scott Howard-Cooper, who covers the NBA for the Sacramento Bee, is a regular contributor to ESPN.com.