LOS ANGELES -- Miguel Montero was scheduled to see Dr. Lewis Yocum for a second opinion on his injured right knee Tuesday in Los Angeles.

The D-backs' catcher has already been diagnosed with a torn meniscus, but the question is whether he also suffered damage to the ligaments in the knee. The team his hoping that's not the case because that will require a longer rehab period.

If it's just a torn meniscus, the timetable for return would be around six weeks.

"He'll get a second opinion from Dr. Yocum and we'll go from there," D-backs manager A.J. Hinch said. "Until then, we don't know."

The injury occurred in the second inning of Saturday's 6-3 loss, when Montero hit a tapper back to Pirates pitcher Zach Duke.

"I was trying to run him over and I felt something pop," Montero said. "I tried to speed up and I felt something pop, and that's when I slowed down."

Montero has been replaced in the starting lineup by Chris Snyder and John Hester was recalled from Triple-A Reno to serve as the backup.

Snyder had a big first day as a starter when he went 2-for-4 with a double, a homer and five RBIs on Sunday against the Pirates.

Rehabbing Webb plays catch

LOS ANGELES -- Brandon Webb played catch for seven minutes at Chase Field on Monday before flying to Los Angeles.

The D-backs right-hander said he started throwing from one knee and then backed out to 70 feet and threw for seven minutes.

"Good," he said when asked how it went. "I didn't feel anything, so that's a good sign. It was all good."

Webb, who had shoulder surgery last August, has found the going slow in his recovery this spring. He last threw a bullpen session in early March, but has not been back on the mound since.

Webb said he planned on playing catch again Tuesday and going to a two days on, one day off program for now.

There is still no timetable for his return.

D-backs near fifth starter choice

LOS ANGELES -- Decision time is looming for the Arizona Diamondbacks.

The club began the year with just four starters in the rotation thanks to a pair of off-days early in the schedule. Come Saturday's game at San Diego, though, the D-backs will need a fifth starter.

The candidates at Triple-A Reno include Kris Benson, Billy Buckner and Kevin Mulvey.

Buckner and Mulvey were outpitched for the fourth spot in the rotation by Rodrigo Lopez this spring and Benson was signed after spring games had gotten under way.

"Well before Saturday," D-backs manager A.J. Hinch said when asked on when he was going to choose a fourth guy. "Probably in the next day or so. We need to game plan a little bit, but I don't really care for the Padres to know quite yet."

Mulvey was set to pitch Tuesday night. Benson pitched Monday and allowed two unearned runs on four hits over five innings. Buckner, meanwhile, allowed seven runs on 10 hits in five innings on Sunday.

While Benson might have performance working in his favor, the thing he does not have is a spot on the 40-man roster. In order to add him, the D-backs would have to move someone off. One possibility would be to place Brandon Webb on the 60-day disabled list which would take him off the 40-man.

Heilman off to a great start

LOS ANGELES -- After Aaron Heilman scuffled in his first couple of Spring Training outings, there was some concern about the right-hander, who was acquired in a trade with the Cubs early last offseason.

The veteran Heilman was not one of those worried, though, he'd been through enough springs to know better.

"You never want to look bad out there," he said. "But you also know the first couple of times, you're working on stuff. You're trying to get your rhythm together, trying to get your timing down, working on getting a feel for your pitches. You don't have to be ready for the season on Feb. 17."

Heilman's preparation has paid early dividends. In three appearances, he has yet to allow a baserunner and D-backs manager A.J. Hinch seems to have slotted him in right behind closer Chad Qualls and eighth-inning man Juan Gutierrez.

Heilman was one of the best setup men in baseball when he was with the Mets in 2006 and '07. His '08 and '09 seasons were a different story as he compiled ERAs of 5.21 and 4.11. The D-backs liked his stuff, though, and that's why they made the push to acquire him.

"We feel like we're going to get a guy that's returning to form and can help us in important innings and he's shown that in the first week of the season," Hinch said.