San Antonio Spurs Coach Gregg Popovich joked earlier this week that he wished he had a machine to detect what was going on in the head of forward Tim Duncan, whose perpetual blank stare says nothing and everything at the same time. Such a machine would have been helpful in the final minutes of the Spurs' embarrassing 102-71 loss against the Detroit Pistons in Game 4 of the NBA Finals as Duncan sat on the bench, never signaling whether he was frustrated, disappointed, angry or dreading having to again confront Detroit's three-headed defender blender of Ben Wallace, Rasheed Wallace and Antonio McDyess.

Duncan's expression likely won't change Sunday during Game 5 at the Palace of Auburn Hills -- whether he overcomes consecutive poor performances with something more in character or whether he continues to shrink and shrivel under the constant barrage of Pistons elbows, hips and knees -- but depending on the result of the game, it won't be too difficult to figure out its meaning. Duncan said the success or failure of the Spurs will rest squarely on his shoulders, which have been slouched more than usual this week.

"It starts with me," Duncan said. "I understand that."

The Spurs have been trounced the past two games, and in many ways, the breakdown began with Duncan. Throughout his career, Duncan has been the player who canceled out the inconsistencies of his teammates. But even he can't be counted on of late, as he has made just 10 of 32 shots in the past two games and has produced just five field goals in each of the past three games.

"It's just frustrating," said Duncan, who is averaging 18 points on 39.1 percent shooting, with 13.5 rebounds and 2.5 blocks in this series. "It's just frustrating, because especially in this time of the year and on this stage, I feel like those shots should be going down for me. I should be able to make those shots.

"But they don't, and they didn't go down, and the frustration is there, of course, and the frustration on a personal level, frustration for my teammates. But I look forward to the next game."

Duncan had dominant performances in Game 5s in the 1999 and 2003 Finals, after which he was named MVP both times. He had 29 points, 17 rebounds, 4 blocks and 4 assists as the Spurs defeated the Nets in 2003. In the series clincher against the Knicks in 1999, Duncan had a team-high 31 points and nine rebounds. But neither the Nets nor Knicks possessed the front court depth and versatility the Pistons have.

The Pistons have the benefit of throwing three defenders at Duncan. They have Ben Wallace, the defensive player of the year, to muscle him around. Rasheed Wallace can use his length and experience, with the two staging battles when Wallace was in Portland and when Wallace and Duncan were in college, at North Carolina and Wake Forest, respectively. They also have McDyess, who can blend both styles, coming off the bench.

"I think they complement each other very well with their styles," Duncan said. "They are all very long and they are all very strong and they are all very active."

They have pushed Duncan out of his comfortable spots on the floor, cut off the driving and passing lanes for the Spurs guards and have flustered Duncan to the point that he is spending more time complaining to the officials for calls.

"I see him get a little frustrated," Ben Wallace said.

Duncan's struggles have been magnified because he hasn't received much help. Point guard Tony Parker has been able to drive but unable to finish. Guard Manu Ginobili, who was well on his way to being the series MVP after the first two games, hasn't been the same player since his left thigh collided with the knee of Detroit's Tayshaun Prince in Game 3. And role players Nazr Mohammed and Robert Horry have all but disappeared.

The Pistons have discovered that taking Duncan out of his game turns the Spurs into a confused, turnover-prone team.

"He's the center of what we do. He's important," Popovich said. "We're an inside-out team. We're going to have something inside going with Tim and spacing the floor is important to us in that regard. So if we don't really have the inside-out game, it takes a lot away from what we're doing."

Duncan hasn't had much luck in Detroit this season, beginning with his severe ankle injury in March which cost him 12 games. But Popovich isn't worried about Duncan's ability to respond.

"He's not going to pout. He's not going to feel badly. He's going to be disappointed with himself for not playing better," Popovich said. "He'll try to figure out what he can do to score, what he can do to help the team. That's just the way he's built."

The Spurs will need Duncan to return to his old form soon. Of the 23 previous Finals that have been tied at two games, the winner of Game 5 has gone on to win the title 17 times (73.9 percent).

"I think this team is so funny that however Tim plays, it kind of dwindles down to the rest of us," Horry said. "But for the most part, I think it's going to have to be more than just Tim. Everybody wants to put all this on Tim, Tim, Tim. But it's a total team effort."

Detroit's physical approach has left Spurs star Tim Duncan flat on his back in the past two games. He is 10 for 32 from the field in those games, both losses.