LISTEN: Jerry Dipoto on the Mariners' top two draft picks, Leonys Martin's return Your browser does not support the audio element.

The Mariners plan to activate center fielder Leonys Martin before tonight’s series opener against the division-leading Rangers, general manager Jerry Dipoto told “Brock and Salk” this morning.

Martin has been on the 15-day disabled list due to a strained hamstring. He took part in a simulated game Wednesday at Safeco Field and was set to play in a rehab game with Triple-A Tacoma last night before he was scratched due to concerns over the wet field conditions. Martin became eligible today, having spent the requisite 15 days on the DL, but manager Scott Servais told reporters last night that the team wasn’t certain about Martin being activated yet. Dipoto told “Brock and Salk” that it will almost certainly happen.

“Hopefully we’re going to be able to activate him before the game, which we’re 99 percent certain is going to happen,” Dipoto said. “He’ll be out there in center field.”

The Mariners begin a three-game series at home against Texas, which Seattle trails by four games in the American League West standings.

Martin was the Mariners’ hottest hitter when he was injured during a stolen-base attempt last month against Oakland. During 22 May games, he was hitting .320 with five home runs and 10 RBIs. The Mariners have missed Martin’s defense just as much as his bat during the two weeks he’s been out.

“It’s critical that we get his defense back in center field and re-situate our club the way it should be laid out,” Dipoto said, “because I think when Leonys is out there, we are exceptional defensively in the middle of the field. And when he’s not, it really shows, and we’re weaker in other areas because we’ve moved players that have strength in one spot and maybe not so much in another.”

Dipoto said Martin looked “terrific” during his simulated game Wednesday, when he swung the bat and ran the bases. The Mariners pulled him from his rehab start last night because they didn’t want him running around on a soggy field.

“We wanted the opportunity yesterday to have him play center field defensively and watch him get his jumps and make sure he was challenged to get off the ball,” Dipoto said. “But just watching him in the batter’s box, that I’m very comfortable is going to go very well. And today we’ll see what he does.”

As for ace Felix Hernandez, Dipoto said the Mariners have to be cautious as to not risk another injury by bringing him back too soon. Hernandez is on the 15-day disabled list with a strained calf, which has forced him to wear a protective boot and kept him from doing any work on his feet.

Dipoto didn’t put a timetable on Hernandez’s return. His comments suggested that it isn’t imminent.

“Felix is more day-by-day for us,” Dipoto said. “We have to behave conservatively here. He’s very important to us, and we have to make sure that when we send him out there to throw, his lower half is capable of torquing the way it does in his delivery. He’s got a very unique delivery, and the way he twists and torques his knees, and right now with the calf, we have to make sure that when he gets over the backside of that rubber that he feels strong back there because if we don’t, it could result in something above the waist, which we don’t want. We don’t want to do anything that’s going to put Felix’s arm health at risk.

“It’s worth waiting an extra day or week or whatever we have to wait to make sure he’s 100 percent. Like the doctors will always reference, we’re going to treat the patient rather than the injury. In this case, we’re just going to wait until Felix is 100 percent before we let him get out there and throw.”