SAN FRANCISCO -- The Giants received bad news on two key relievers Monday.

Reyes Moronta will undergo surgery to repair a torn labrum and capsule in his right shoulder Tuesday in Los Angeles. Tony Watson is likely lost for the season, too, as an MRI exam Monday revealed a small fracture in his left wrist.

The injuries to Moronta and Watson leave closer Will Smith as the only member of the Giants’ Opening Day bullpen remaining on the active roster. Smith hasn’t pitched since Friday due to back tightness, but manager Bruce Bochy said that he’s improving despite not being used in a save situation during Monday night’s series-opening 6-4 loss to the Pirates.

Moronta suffered the injury during a relief appearance against the Padres on Aug. 31, as he crumpled to the ground after throwing a 97-mph fastball to Luis Urias.

Bochy said that the Giants will have a better idea of Moronta’s timetable following the surgery, but the timing of the procedure will likely imperil his 2020 season as well. Moronta will be treated by Dr. Neal ElAttrache, who also performed labrum surgery on Dodgers left-handers Hyun-Jin Ryu and Julio Urias. Ryu missed 14 months before returning to pitch in the Majors after his shoulder surgery.

Moronta, 26, logged a 2.86 ERA over 56 2/3 innings this year and had moved into more of a setup role after the Giants dealt Mark Melancon, Sam Dyson and Drew Pomeranz at the Trade Deadline. Moronta has already overcome one significant arm injury in his career, as he underwent Tommy John surgery while pitching for Class A Salem-Keizer in 2013. 

Watson hurt his wrist while making a diving tag that helped the Giants hang on for a 9-8 win over the Cardinals on Wednesday. X-rays initially came back negative, but Watson continued to feel discomfort after attempting to throw Sunday in Los Angeles. He was examined by Dr. Scott Hansen, the Giants’ hand specialist, Monday morning and later received a phone call informing him of the fracture.

Watson’s wrist will be immobilized for 10 days before he is re-evaluated by the Giants’ medical staff. The 34-year-old left-hander said that he hopes to pitch again this year, though he recognizes that the clock is working against him. 

“I would like to, so I can finish it out on a good note,” Watson said. “But I’m also aware of the timeline and aware of the season. This is all fresh. It’s frustrating, but we’ll get more information here tonight and go from there.”  

Watson, who has a 4.33 ERA over 54 innings this season, has a $2.5 million player option for 2020, though he will have the option to decline it and become a free agent this offseason. 

Triple-A Sacramento continues playoff run

The Sacramento River Cats defeated the Las Vegas Aviators (A’s Triple-A affiliate) on Sunday to advance to the Pacific Coast League championship series. They will face the Round Rock Express (Astros) and vie for the franchise’s fifth PCL crown and first since 2008.