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3/21/2014 10:36 P.M. ET

Iwakuma uses tennis ball to build up arm strength

Walker, Pryor to make debuts Saturday against Padres' Minor Leaguers

PEORIA, Ariz. -- Injured All-Star Hisashi Iwakuma threw a tennis ball Friday in his first step back from a six-week layoff with a sprained finger tendon, while young Mariners right-handers Taijuan Walker and Stephen Pryor are scheduled to make their spring debuts in Minor League games Saturday.

The three injured hurlers could all be critical factors for Seattle this season, so their progress is being closely monitored. All three will presumably open the regular season on the 15-day disabled list, given there are only 10 days until the Mariners face the Angels in Anaheim on March 31.

Iwakuma, 32, will need to slowly build back up his arm strength over the coming weeks. He began the throwing program with a tennis ball inside the Mariners' training room, just to work on strengthening his grip after not being able to hold a baseball the past six weeks.

"I threw about 40-45 times with a tennis ball inside the weight room," Iwakuma said. "I felt good, no pain, better range of motion. So far, so good."

The Mariners won't rush the process with the right-hander, who went 14-6 with a 2.66 ERA last season and finished third in the American League Cy Young voting. He'll need to build up to long-toss and then throwing bullpen sessions before taking the mound for his own Minor League rehab appearances sometime in April.

"I'm happy he's back out and starting to be active again," manager Lloyd McClendon said, "but it's going to take a little while. It's not going to happen overnight. We just need to get him moving forward."

Walker, who is ranked the Mariners' top prospect and was projected to land a starting-rotation job coming into camp, hasn't pitched in a game since arriving in camp with a sore throwing shoulder and later being shut down for a week after being diagnosed with bursitis.

Walker has thrown three bullpen sessions in recent days and now will begin testing his arm in game situations, with a scheduled 20 pitches Saturday in an outing against the Padres' Class A club at the Mariners' practice complex at 1 p.m. PT.

"I'm pumped," said the 21-year-old. "When they told me they'd get me in a game with 20-30 pitches, I'll take it. I'll take whatever it is. This is a big test. I don't want to go out there blowing it out. It's going to be tough holding it back, but I want to go out there with fastballs and changeups and just work on location, throwing at 80-85 percent and just keep it there. If everything goes good, we'll move forward."

"Ideally, we'd like to see him go two innings and see how it goes," McClendon said. "It's a Minor League game, so we can control it and go from there."

Pryor, 24, hasn't thrown in a game since a Minor League rehab outing last July, when the hard-throwing reliever discovered he was having further issues with a torn latissimus dorsi muscle behind his right shoulder that initially sidelined him two weeks into the Mariners' season.

Pryor is scheduled to follow Walker on Saturday with a 20-pitch inning of his own in the Minor League game in Peoria, Ariz.

"I'll get in there and see how it goes," Pryor said. "It's a big step for me. I'm excited about it."

Pryor has thrown five bullpen sessions and three batting practice sessions this spring, clearing every hurdle while increasing his strength and velocity. Pryor was expected to be a key member of last year's bullpen and had thrown 7 1/3 scoreless innings in the first two weeks of the year when he initially tore the lat muscle.

If Pryor can return at full strength in the early going this season, that would be a significant boost to Seattle's relief crew. And the big right-hander feels that is certainly possible.

"I'm not coming up sore or hurt, so this is the next step in the progression," Pryor said. "I set high goals for myself, so I was hoping to be ready to go April 1. That's not the case. I don't know where they have me, but if I could be back in mid-April, before May sometime, that would be great, in my opinion. But we'll have to wait and see how the progression goes."

McClendon still 'tinkering' with lineup

PEORIA, Ariz. -- Manager Lloyd McClendon had Abraham Almonte in the leadoff spot Friday night against the Padres, the 16th time in 25 Cactus League games he's penciled the young center fielder into that position.

But McClendon said he's not ready to pronounce Almonte as his leadoff hitter for the regular season.

"Down here, he has been," McClendon said. "But I'm not ready to make those type decisions. We're still tinkering with our lineup. You could see other guys leading off. You'll see somebody else leading off one of the games tomorrow."

That's because the Mariners have a split-squad situation Saturday and Almonte can only lead off one of the games. But so far this spring, he's been in that role the vast majority of contests, with Endy Chavez (five), Brad Miller (two) and Dustin Ackley and James Jones (one each) the other leadoff hitters.

Almonte was hitting just .160 (8-for-50) with two doubles, two home runs and three stolen bases going into Friday night's game. But McClendon likes the skill set of the 24-year-old and used Thursday's game against the Cubs as an example, after Almonte singled, stole second, moved to third on a wild pitch and scored on a sacrifice fly.

"I like what I've seen," McClendon said. "Obviously he hasn't gotten the positive results that equate to having a successful Spring Training, so to speak. But he's done some nice things. He's hit the ball on the barrel for the most part. He's made solid contact. We all saw what his speed could do yesterday. There are a lot of good things."

The new skipper continues moving other hitters around in his lineup. He had Miller up in the two-spot against the Padres, with Kyle Seager dropped to fifth.

"I'm just tinkering around to see what fits best," he said. "We'll do a little more tinkering. You may see Seager hit fourth, I don't know. We'll see where we are."

One spot that won't be changing: Robinson Cano will be batting third.

"Not much tinkering there," McClendon said with a laugh.

Prieto promoted to coach for Major League staff

PEORIA, Ariz. -- Chris Prieto, who had been slated to manage the Class-A Clinton club in the Mariners Minor League system, instead was promoted to the Major League staff on Friday as a quality control coach.

Manager Lloyd McClendon said Prieto, 41, will serve as the go-between for the Mariners' advance scouting department and the Major League coaching staff.

"He'll coordinate with the statistical analysis people and be the liaison between that department and our coaching staff, making sure our scouting reports are right-on and have the things we want and need, and eliminate the things we don't need," McClendon said.

"He'll be in charge of defense and how we position, a little more in-depth scouting on how we position players as we move forward during the season."

Prieto is in his second year in the organization. He managed the Rookie League Pulaski club to a league-best 41-27 record last year after previously coaching in the Padres' farm system. Prieto was an outfielder for 13 years in pro ball and played two games with the Angels in 2005.

He'll travel with the team and throw batting practice and take part in pregame drills, but won't be in uniform during games due to the limit of coaches allowed in the dugout.

McClendon said the position is one that he and general manager Jack Zduriencik have been talking about for some time.

"As we move forward, I think it's a good idea, and something most clubs are moving toward, to give us that eye in the sky, so to speak," McClendon said. "He'll give a little different perspective, not only the ability to scout other teams, but also scout ourselves. If there's something we need to do different or a weakness we can shore up, that's something we need to look into and I think he'll be a big help for us."

Worth noting

• Left-handed reliever Joe Beimel said he's back to feeling 100 percent after pitching for the first time in 12 days with a perfect inning Thursday against the Cubs. Beimel is coming back from Tommy John surgery, but said inflammation in his elbow last week apparently was due instead to a virus he caught that got into his joints.

"Never had that happen before," he said. "But everything is feeling fine now and yesterday was the best I've thrown all spring."

• Right-hander Brandon Maurer threw a bullpen session Friday as he began his return from a sore back and neck that have sidelined him since March 10.

• If Cano can push his spring total up to the necessary 50 at-bats to be included in Cactus League records, he has an excellent chance to set a Mariners record for highest spring batting average. Cano was hitting .567 (17-for-30) going into Friday night's game. The club record is .492 (32-for-65) by Michael Morse in 2008.

Ackley's .457 mark (21-for-46) going into Friday's action would rank him seventh all-time on the Mariners' spring list.

Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.