JUPITER, Fla. — St. Louis closer Luke Gregerson will begin the season on the disabled list with a hamstring strain, manager Mike Matheny said on Saturday.

Gregerson injured the hamstring during conditioning drills. He hasn't pitched in a Grapefruit League game since Tuesday, when he struck out two in an inning. There is no announced timetable for his return.

"Hamstrings are so difficult to predict," Matheny said.

The Cardinals signed Gregerson during the off-season to be their closer. He saved 31 games for Houston in 2015 and 15 more the following season.

Gregerson worked three perfect innings this spring for the Cardinals.

"He's frustrated, too," Matheny said. "He's had a long career and been a guy that's been durable."

Earlier this spring, Gregerson missed time because of oblique tightness. Matheny said he didn't believe the two issues were related.

"He bounced back pretty quick which is hopefully an indicator of how quickly he's able to bounce back from injury," Matheny said.

Without Gregerson, Matheny intends to select his closer on a game-by-game basis based on matchups. Righties Dominic Leone and Bud Norris, along with lefty Tyler Lyons, figure to be in the mix.

St. Louis acquired Leone in the off-season trade that sent Randal Grichuk to Toronto.

Entering Saturday's game against the New York Mets, Leone allowed only one run while striking out 11 in eight appearances this spring.

"He's got swing-and-miss stuff," Matheny said. "The cutter in particular plays extremely well for me in the fact that it is a four-seam cutter. It's not something that you see or expect to move like it does. We're always looking for a guy with a pitch that may be different than what other people have."

Lyons came through the St. Louis organization as a starter before moving to the bullpen. He appeared in 50 games for St. Louis last season. Entering Saturday, Lyons allowed three runs this spring.

The Cardinals signed Norris as a free agent after the start of camp. Primarily a starter throughout his career, Norris saved 19 games for the Angels last season.

St. Louis began the spring by stretching out Norris so he could potentially start or pitch in long relief, but moved him to the bullpen for the final two weeks.

"He's got good stuff," Matheny said.

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