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9/3/2013 8:40 P.M. ET

Felix on track for Sunday despite back issue

KANSAS CITY -- One day after being removed from his start against the Royals for precautionary reasons due to a lower back cramp, Mariners ace right-hander Felix Hernandez was still in line to make Sunday's start against the Rays on five days' rest.

Hernandez on Monday left on a hot day in the seventh inning after throwing 105 pitches in the Mariners' 3-1 loss.

"Felix is a little bit sore, a little bit stiff today," manager Eric Wedge said before Tuesday's game at Kauffman Stadium. "So, we will monitor that from day to day. It's the first day after and you figure he's going to feel that. We'll see how he feels the next couple of days and go from there."

Lefty Paxton among four callups for Mariners

KANSAS CITY -- Left-hander James Paxton is ready for his big opportunity at the Major League level. The Mariners' fourth-round pick in the 2010 First-Year Player Draft was one of four callups on Tuesday and will get the opportunity to start on Saturday against Tampa Bay at Safeco Field.

"I didn't know what was going to happen," Paxton said. "I was hoping to get an opportunity and I'm just happy that I'm here. I can't wait to get my chance."

Paxton, 24, went 8-11 with a 4.45 ERA in 28 appearances [26 starts] for Triple-A Tacoma. He struck out 131, averaging 8.09 strikeouts per nine innings.

"It was been an up-and-down season for me," Paxton said. "At the beginning of the year, I kind of struggled while learning the league. I got to know the batters better, got more confidence and rattled off some good outings. Then, I had a couple of rough ones, but I feel like I finished strong. I'm coming in feeling pretty good about my stuff and where I am."

Paxton said that, through his experience in Triple-A, he has developed confidence in throwing offspeed pitches behind in the count. He has mixed a cutter into his repertoire and is enthused about an improving changeup.

"It's great to get those 'firsts' out of the way," manager Eric Wedge said. "He has worked hard to get here and deserves to be here. You get a chance to compete at the highest level and work off where you are from there."

Besides Paxson, the Tuesday callups following the completion of Tacoma's season were right-hander Chance Ruffin, right-hander Hector Noesi and infielder Carlos Triunfel. Tacoma hitting coach Howard Johnson was also added to the Mariners' staff for September.

Ruffin, 24, returns to the Major Leagues for the first time since 2011. He split the season between Double-A Jackson and Tacoma, combining to go 5-6 with a 3.91 ERA.

Noesi, 26, is beginning his fourth stint with Seattle this season. In nine appearances with the Mariners, he was 0-1 with a 5.64 ERA. Both Ruffin and Noesi will be expected to help bolster the bullpen. Triunfel, 23, appeared in nine games with the Mariners over two stints before the All-Star break, going 2-for-24 at the plate.

The active roster now includes 32 players. With the addition of Paxton, the 40-man roster is full. Right-hander Stephen Pryor is on the 60-day disabled list and first baseman/designated hitter Jesus Montero is on the restricted list.

Mariners gain flexibility with six-man rotation

KANSAS CITY -- With an eye toward reducing the wear-and-tear on some of the established starters and getting a look at promising prospects, the Mariners have decided to come down the stretch in September with a six-man rotation.

Erasmo Ramirez got the start on Tuesday, while Taijuan Walker and Joe Saunders will work in the final two games of the Kansas City series. Hisashi Iwakuma is scheduled to open the homestand on Friday against Tampa Bay, followed by James Paxton in his Major League debut on Saturday and ace Felix Hernandez on Sunday.

"It allows us to have some options and flexibility, which is a good thing this time of year," manager Eric Wedge said.

Through Tuesday, Hernandez has worked 194 1/3 innings, Iwakuma had 191 innings and Saunders was at 162 2/3 innings. Wedge said the innings load will take care of itself with the six-man rotation.

Robert Falkoff is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.