Furcal left a rehab assignment with the team's Triple-A affiliate in Las Vegas on Tuesday and returned to Los Angeles after experiencing discomfort in his back. He has been on the disabled list since May 6 because of a lower back strain.
The Dodgers said Furcal would undergo a microdiscectomy. Torre said Furcal will miss "a minimum of eight weeks."
Furcal played four innings with Las Vegas on Monday night, going 1-for-3 with a double and an RBI.
Torre said Furcal didn't injure himself in the game, but woke up Tuesday morning with back discomfort. Furcal flew to Los Angeles and underwent tests before he agreed to have surgery.
"It's a blow, but it's reality," Torre said after the Dodgers' 4-1 win over the Houston Astros. "He went out there, played a game and that was that. It's frustrating. He was, from what I understand, ready to just do this and get it done and get it over with. They anticipate this will solve everything."
Furcal missed the final two weeks of last season with back pain and played in just 32 games this season before going to the DL. He was hitting .366 with five homers and 16 RBIs.
Torre admitted that he was optimistic when Furcal took the field on Monday.
"After the first time, when he thought he felt good, it just didn't work out that way," Torre said. "I got a little tempted this time when we ran him out there. Talking to him, he didn't seem to have any hesitation. I guess I got excited again."
Luis Maza started at shortstop on Wednesday. Torre said he'd also use Angel Berroa there and may consider Nomar Garciaparra there when he comes off the disabled list. Garciaparra has been on the DL since April 26 with a strained left calf, but could return before the All-Star break.
"I will certainly look at Nomar at shortstop, but I'm certainly not thinking on an everyday basis," Torre said. "I don't think that's fair to Nomar. We'll try to figure it out and probably play piecemeal between now and the All-Star break."