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 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 Tuesday.

A major problem was at the free throw line, where the Grizzlies were 10 of 18 on Saturday night. Memphis shot 77 percent from the line in the regular season but left too many points off the board.

"Who knows why we're missing as many free throws as we are right now?" said Pondexter, who missed his only free throw. "We've got to concentrate a little more I guess. I have no idea. We shot great during the season. It's a game of averages. I think what we did in the regular season is kind of kicking us right now."

At this point, Memphis will have to concentrate on everything in Game 4 to avoid a sweep similar to the one the Grizzlies sustained in 2004 at the hands of the Spurs in the franchise's first postseason appearance.

"We still have to have the mindset of one game at a time," Allen said. "Obviously, we've got one more game (Game 4 on Monday night) at home. We showed a better effort from start to finish. Well, for four quarters. We've got to have some carry-over going into the next game with that mentality minus the overtime."

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."

Notes: Conley had five steals in the first quarter, the most in a quarter of a playoff game over the past 10 postseasons, according to Elias Sports Bureau. He finished with five turnovers. ... The Grizzlies had their 16th straight postseason sellout. ... The Spurs now have played five overtime periods this postseason, the most in franchise history. ... The Grizzlies are 1-2 in overtime games this postseason. ... Randolph had his seventh double-double, most in the NBA this postseason. ... Duncan had his 144th postseason double-double, moving into second by himself behind Magic Johnson.