GLENDALE, Ariz. -- Madison Bumgarner will make his second straight Opening Day start for the Arizona Diamondbacks when they travel to face the San Diego Padres on Thursday.

Manager Torey Lovullo said on Sunday the four-time All-Star would lead the rotation despite a rough 2020 season, when he had a 1-4 record and 6.48 ERA. He'll be followed in the rotation by Merrill Kelly, Caleb Smith, Taylor Widener and Luke Weaver.

Bumgarner signed an $85 million, five-year contract before last season but didn't look anything like the dominant pitcher he was for much of his 11 seasons with the San Francisco Giants, where the left-hander helped the franchise win three World Series titles.

The 26-year-old Widener takes the rotation spot of right-hander Zac Gallen, who was in contention for the Opening Day start before a hairline fracture was discovered in his right forearm. He suffered the injury while getting jammed during batting practice.

Gallen was one of the best pitchers in the National League last season, finishing with a 3-2 record, 2.75 ERA and 82 strikeouts in 72 innings. He finished ninth in the NL Cy Young Award voting. Lovullo said he's unsure how much time Gallen will miss.

Widener will be making his first big league start. The right-hander, who pitched in college at South Carolina, had a 4.50 ERA in 12 relief appearances in 2020.

Lovullo also said Sunday that starting shortstop Nick Ahmed was battling soreness in his right knee and received an injection, though the manager is hopeful Ahmed will still be ready for Opening Day. If Ahmed is limited, Josh Rojas could be the part-time starter.

The 26-year-old Rojas has started just two big league games at shortstop but Diamondbacks management was impressed at how he handled the position during spring training. He can also play at second base or in the outfield.

The D-backs also moved closer to finalizing their Opening Day roster by sending outfielder Trayce Thompson and pitchers Joe Mantiply and Anthony Swarzak to minor league camp. That likely means that utility players Josh VanMeter and Wyatt Mathisen, along with veteran reliever Chris Devenski, have secured a spot on the roster.