The Memphis Grizzlies have made a habit of falling behind in series this postseason.

This time, they may be down too far to survive.

For the second straight game, Memphis couldn't finish off the San Antonio Spurs in regulation, then had breakdowns in overtime. They allowed the Spurs to pull out a 104-93 victory on Saturday night that left Memphis on the verge of being swept out of the franchise's first Western Conference finals.

"I can't really explain it," Memphis guard Tony Allen said. "Down 0-3, and it's just an unfortunate situation that we're in. We've got to claw our way back into this series."

Memphis was down 0-2 to the Los Angeles Clippers in the opening round before winning the next four. The Grizzlies lost to the Oklahoma City Thunder in the opener of the semifinal round, then reeled off four straight.

Losing for the first time this postseason on their own court may be a bit too much to overcome. To move to the NBA Finals, the Grizzlies have to become the first NBA team to win a series after losing the first three games.

"It's been a lot of pain, but we've got to play," said Memphis center Marc Gasol, who had 16 points and 14 rebounds. "There's no excuses. None. We've still got to play. We won't give up."

Mike Conley led Memphis with 20 points, while Quincy Pondexter had 15 off the Memphis bench. Zach Randolph finished with 14 points and 15 rebounds. Allen had 12 points.

The Grizzlies looked like they were going to hold home court after dropping the first two games in San Antonio, including a 93-89 overtime loss in Game 2. Memphis jumped out to an 18-point, first-quarter lead, as the Spurs shot 21 percent in the period and committed eight turnovers.

But Memphis couldn't maintain the advantage. Eventually, the fourth quarter came down to a close showdown that included 11 lead changes and nine ties.

The ninth tie came when Allen split a pair of free throws with 33.9 seconds left in regulation, leaving the teams deadlocked at 86.

Tim Duncan, who finished with 24 points and 10 rebounds, dominated the extra period, just as he did on Tuesday.

The Spurs hit eight of their 10 shots in overtime, with Duncan scoring the first five. Tony Parker had five of his 26 in overtime, and even Tiago Splitter, playing with four fouls, scored six in the extra five minutes to finish with 11.

"He was huge for us the other night in overtime and got it done for us, and he did it again tonight," Spurs coach Gregg Popovich said of Duncan, the two-time MVP. "That's why he is considered as great as he has for the last 17 years. He's been unbelievable. He feels a responsibility to carry us in those kinds of times, and he did it again tonight."