Kyle Lewis' knee injury has become far more concerning after a medical exam on Saturday revealed “a pretty deep bone bruise,” according to Mariners manager Scott Servais. Lewis was out of the lineup against the Giants for the fifth straight game, and his status for Opening Day is in doubt.

“I'm as surprised as anybody, based on what we thought here the first couple days,” Servais said. “But it makes sense that it hasn't really responded the way he or the training staff was hoping it would. But we are getting close to Opening Day, so I guess it puts that in jeopardy a little bit.”

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Lewis is experiencing inflammation in the area, which he hurt while awkwardly colliding with the wall on Monday against the Dodgers. The Mariners have not begun outlining a robust rehab plan, in large part because they weren’t aware of the severity of the injury.

“He'll be out and certainly won't play down here in the Cactus League,” Servais said. “We’ll just have to wait and see when he can get back. I don't want to go too far down the rabbit hole. Hopefully he can knock this out and be back with us soon. But it's concerning, no question.”

If Lewis were placed on the 10-day injured list to begin the season, it could be retroactive to March 29, which would make him eligible to return on April 8 against the Twins, a span of just six regular-season games. But beginning the season without the reigning American League Rookie of the Year -- who is also one of the club’s top run producers -- is far from ideal, particularly given the lack of outfield clarity beyond Lewis and Mitch Haniger.

Taylor Trammell has had an impressive spring, but the club’s No. 6 prospect hasn’t yet played in the Majors. And if Trammell were to move to center field, that would open the door in left for Jake Fraley, who has been on an offensive upswing lately after beginning the Cactus League slate hitless in his first eight games.

Jarred Kelenic was reassigned to Minors camp on Friday, and it seems unlikely that the club would opt for its No. 1 prospect to make his MLB debut under the circumstances of being an injury replacement, especially given that it has been this patient with his development to this point.

Servais also didn’t rule out the club exploring external options.

Gerber, Swanson optioned to alternate site
In a somewhat surprising roster move, the Mariners optioned relievers Joey Gerber and Erik Swanson to the alternate training site on Saturday. Both were favored to make the team after strong springs, and in Swanson’s case, he has multi-inning ability.

Gerber, the club’s No. 30 prospect, was scoreless in seven of his nine Cactus League outings, but he gave up a combined seven runs in the other two. Swanson gave up two runs, including a homer, in his Cactus debut, but he was scoreless in his final six times out.

The other candidates -- Will Vest and Drew Steckenrider -- offered a lot of upside but with mixed results. As such, they were considered wild cards. But now it seems that those two will indeed break camp with Seattle.

Pitching probables for season-opening series
The Mariners were the first club to announce their Opening Day starter when they gave Marco Gonzales the nod for the third straight year on the fifth day of camp. On Saturday, Servais outlined who would follow the left-hander in the season-opening series against the Giants.

James Paxton will pitch the second game on Friday and Chris Flexen will take the hill for Saturday’s series finale. Sunday, April 4, is an off-day, then the Mariners will host the White Sox for a three-game series.

Servais was not ready to divulge who would start in the next series, though the candidates would be Yusei Kikuchi, Justus Sheffield and either Justin Dunn or Nick Margevicius.

Paxton ready for regular season
Paxton’s final tuneup for the regular season was another gem. Big Maple struck out nine over four innings Saturday night in a 5-0 win over the Giants to put a bow on his Cactus League slate, reaffirming to himself and the Mariners that he’s healthy.

“I think it was big,” Paxton said of pitching in an “A” game instead of on the backfields. “I think that getting out there in the real game atmosphere, getting used to having an umpire back there, guys playing behind you, I needed to do that again before the season started.”

Paxton said he was excited to get back to T-Mobile Park and pitch in front of a sold-out crowd of 9,000 on Friday.

“I can't wait to get back to T-Mobile Park and play in front of the fans," Paxton said. "It's going to be be awesome to be back in Seattle and get this thing started."