WEST PALM BEACH, Fla. -- For the second straight day, a strained left hamstring will send the Cardinals north without a veteran pitcher. Sunday the club revealed Adam Wainwright will begin the season on the disabled list after the 36-year-old starter was injured during conditioning drills earlier in the week.

Jack Flaherty will serve as the club's No. 5 starter in Wainwright's absence, Cardinals manager Mike Matheny said.

The news comes a day after the club learned it would open the season without reliever Luke Gregerson, who also strained his hamstring during conditioning drills. Matheny called Wainwright's strain less severe than Gregerson's, but the timeline for either's return is unclear.

"It's one of those things we have to be so careful about," Matheny said. "It has a tendency to really linger if we don't take care of it."

:: Spring Training coverage presented by Camping World ::

The Cardinals were lining Wainwright up as their No. 2 starter early on, in large part to slot him for the home opener at Busch Stadium on April 5. It was an honor the club felt Wainwright deserved heading into the final year of his contract.

"It's something we put thought into," Matheny said. "I think our fans appreciate it, what he's been able to do. 'Waino' obviously has a long history with our fan base and a lot of credibility built up in this game."

Wainwright will now miss that assignment, as well as the second game of the regular season, at least. Wainwright was penciled to start Saturday in New York against the Mets.

Wacha will instead make those starts, lining up behind only ace Carlos Martinez in the Cardinals rotation. Luke Weaver , Miles Mikolas and Flaherty will fill out the back end, in that order.

For Flaherty, it's an opportunity that comes earlier than expected. The 22-year-old was optioned to Triple-A Memphis last week, one of the final cuts of camp after impressing club officials with a swing-and-miss spring. The club's No. 2 prospect per MLB Pipeline, Flaherty struck out 20 batters over 13 innings in Grapefruit League play, after which Cardinals president of baseball operations John Mozeliak called him "the next man up."

"Go get ready," Matheny said he told Flaherty last week. "There is no question that if an opportunity jumped up, we'll be in very good hands."

"He thought I was lying," Matheny said Sunday.

One of the most beloved and decorated pitchers in Cardinals history, Wainwright reported to camp 25 pounds lighter and determined to return to his former level of production. The right-hander required offseason elbow surgery after going 12-5 with career-worst 5.11 ERA in 2017, battling health and velocity issues that this spring seemed resolved.

He pitched to a 0.84 ERA over three Grapefruit League starts, and most recently struck out 10 hitters in a Minor League game last week.

Wainwright was scheduled to pitch Sunday against the Nationals, but was scratched late and replaced with hard-throwing prospect Jordan Hicks .