MESA, Ariz. (AP) — Oakland Athletics pitcher Jharel Cotton will undergo season-ending surgery on his right elbow.Cotton had been diagnosed with a sprain and had a second scan taken on his elbow on Friday, then was told he would need Tommy John surgery. The procedure is expected to take place next week."It's tough. I'm missing the 2018 season with my boys, so it's kind of hard to take. I'm trying to take it as best as I can and just get ready for the long process, the long road that's ahead," Cotton said Saturday morning at A's spring training.The 26-year-old Cotton was expected to be in Oakland's starting rotation this season after going 9-10 with a 5.58 ERA average in 24 starts as a rookie in 2017."Unfortunate. Just of him having to go through what a lot of guys have to go through," A's manager Bob Melvin said. "But we felt like he was on the cusp of really coming into his own and it's going to be delayed a year, unfortunately."The A's figure to go into the 2018 season with Kendall Graveman, Sean Manaea and Daniel Mengden in the rotation. They are still evaluating other starters, but Cotton's loss means more decisions for the rotation and for a possible long reliever.Right-handers Paul Blackburn and Andrew Triggs have also made starts in spring training games, as was prized prospect A.J. Puk, a lefty."There's a trickle-down to the Cotton effect," Melvin said. "It was looking like he would be in our rotation, for sure, someone else is going to have to step up as far as that goes. Once we decide the five than we'll take a look at who our length would be."