Arizona general manager Josh Byrnes said on Friday that reliever Tom Gordon, who had elbow surgery last year, will likely not see Major League action until the third week in April or early May.

"I don't think Opening Day is that realistic," Byrnes said after consulting with team physician Michael Lee as well as the training staff. "He feels great, but we just don't want to push it. This is just our medical opinion based on when he had the surgery that this is an appropriate time line before we get him back on the mound."

Gordon, who was signed earlier this month, has said in recent days how good his right arm feels coming off of ulnar nerve decompression surgery, but the D-backs are taking more of a long term view when it comes to his contributions. He will begin throwing off the mound in two to three weeks.

"Look at September of 2007 when the Phillies were chasing down the Mets," Byrnes said of Gordon, who was with Philadelphia at the time. "He pitched a high volume of innings and pitched great. We want to have him available for that time of year."

With Gordon out for Opening Day, just four pitchers are assured of spots: closer Chad Qualls, Tony Pena, Jon Rauch and left-hander Scott Schoeneweis.

That leaves three spots yet to be determined.

"I would say one of the remaining spots has to be a guy that can be a spot starter or long guy," Byrnes said.

Pitchers that fit that description include Yusmeiro Petit, Billy Buckner, Juan Gutierrez and Travis Blackley.

Both Petit and Blackley are out of options and would need to be placed on waivers if they don't make the team.

Blackley probably didn't help his chances on Friday. The left-hander was seen entering the clubhouse at around 11:45 a.m. MT, more than two hours after the workout began. Not long after practice ended, D-backs manager Bob Melvin, assistant GM Peter Woodfork and farm director A.J. Hinch huddled with Blackley behind closed doors in the manager's office.

When asked to comment on whether Blackley was late or was fined, Melvin said, "It's an internal matter and it's been handled," and he declined to elaborate.

The other two spots in the bullpen have a host of candidates, including those mentioned above as well as Leo Rosales, Doug Slaten and the newly acquired Bobby Korecky, who was claimed off waivers from the Twins on Wednesday.

It's also possible that one of the club's young pitchers could impress enough during camp to get a shot. And there's always Jailen Peguero, who was designated for assignment to make room for Korecky. Peguero cleared waivers and will return to camp on Saturday as a non-roster invitee.

"We'll just have to see how it shakes out," Byrnes said.