CBSSports.com reported that Fernandez, who was placed on the 15-day disabled list with a sprained right elbow Monday, will get a second opinion from the Marlins' team doctor after another physician discovered a tear in the UCL in his pitching arm and recommended surgery.
A source familiar with Fernandez's elbow issues declined to confirm the torn UCL diagnosis to ESPN.com, but said that Fernandez has further doctors visits planned and that the situation "isn't promising medically."
National League sources told ESPN The Magazine's Buster Olney on Monday that Fernandez will need season-ending elbow surgery.
A bevy of pitchers has been diagnosed with torn elbow ligaments requiring Tommy John surgery since the start of spring training. They include Braves right-handers Kris Medlen, Brandon Beachy and Cory Gearrin; Diamondbacks ace Patrick Corbin; Athletics starters Jarrod Parker and A.J. Griffin; Rays All-Star Matt Moore; Yankees starter Ivan Nova; Padres starter Josh Johnson; Mets closer Bobby Parnell; Royals setup man Luke Hochevar; Tigers reliever Bruce Rondon; and top Pirates prospect Jameson Taillon.
Fernandez, 21, is 4-2 with a 2.44 ERA in eight starts this season. He leads the majors with 70 strikeouts.
Fernandez's fastball averaged 94.6 mph over his first four innings in his most recent outing against the Padres but only 90.7 mph over his last two, according to ESPN's Stats & Information. He allowed four runs in the sixth inning before being removed with nobody out.
Last season Fernandez made 28 starts, going 12-6 with a major league-best .182 opponents' batting average. His 2.19 ERA was second in the majors behind three-time defending ERA champ Clayton Kershaw. Fernandez struck out 187 batters and was named NL Rookie of the Year.
Information from ESPN MLB Insider Buster Olney, ESPN's Jerry Crasnick and The Associated Press was used in this report.