KANSAS CITY -- Mariners veteran Felix Hernandez has been placed on the 10-day disabled list, and recently acquired southpaw Marco Gonzales was recalled from Triple-A Tacoma. He will start Game 1 of Sunday's doubleheader against the Royals at Kauffman Stadium.
Hernandez is dealing with tendinitis in his right biceps and the move is retroactive to Wednesday, meaning he won't be available again until next Sunday's series finale against the Angels.
Manager Scott Servais said Hernandez flew back to Seattle on Saturday to see the Mariners physicians, and he's not sure at this point how long the 31-year-old will be out.
"He had some inflammation in his [upper arm] and isn't feeling good at all," Servais said. "He felt it a little coming out of his last start in Texas. He didn't feel great the last couple days. Just talking it over yesterday, we decided it was best to shut him down for a little bit and try to get him back feeling good again."
This will be the second DL stint of the season for Hernandez, who is 5-4 with a 4.28 ERA in 13 starts. He missed nearly two months from April 26-June 23 with right shoulder inflammation, but Servais said he didn't know if the new issue was related.
The six-time All-Star had only been on the DL twice in his career -- in 2007 with an elbow issue and '08 with a sprained ankle -- until missing seven weeks last season with a strained right calf muscle.
The Mariners have the best record in the AL since the All-Star break at 13-8, and they pulled within 1 1/2 games of the Royals for the AL's second Wild Card spot with a 6-4 win on Friday, but they now will go for a time again without the man who has been their Opening Day starter for nine straight years.

"That's bad news," said designated hitter Nelson Cruz, who was back in the lineup Saturday after missing Friday's game with a back spasm. "It's hard. But we can't expect to go the whole year without losing key players. You never want to see that. We faced it early this year and last year. You never prepare for that, but there's nothing you can do but go out and play and try to do your best."
Gonzales, 25, has gone 2-0 with a 4.50 ERA in two starts with Tacoma since being acquired from the Cardinals for Minor League outfielder Tyler O'Neill on July 21. In 13 combined starts with Tacoma and Triple-A Memphis, Gonzales is 8-4 with a 3.14 ERA.
The former Gonzaga University standout has pitched in parts of three seasons with St. Louis, with a 4-2 record and 5.53 ERA in 12 games (seven starts). He is the Mariners' No. 11 prospect, per MLBPipeline.com.
"People in our organization feel very highly on him," Servais said. "I have a little history with Marco. I saw him pitch in high school and college. I have a pretty good idea what we're getting. He's a guy who is very competitive, has good stuff and has been in the big leagues before. So this will be his opportunity."
Gonzales was slated to become the 34th pitcher to appear in a game for Seattle this year, the most of any team in the Majors this season. The club already broke the franchise record of 32 set in 2016. He'll be the 15th starting pitcher used by the Mariners, which also leads the Majors.
Gonzales made one spot start for St. Louis this season, allowing six hits and five runs in 3 1/3 innings in an 8-5 loss to the Brewers on June 13. He made his Major League debut in 2014, and he posted a 4.15 ERA in 10 regular-season games that year, including five starts, as well as six games in relief in the postseason. But Gonzales had health issues the following year, and he then sat out all of '16 following Tommy John surgery.