CORVALLIS — Pat Casey rarely names a starting pitcher until it is required and that will certainly be the case at this weekend's NCAA Corvallis Regional.

Oregon State has one of the nation's top starters in Luke Heimlich and a solid No. 2 option in Bryce Fehmel, but the rest of the starting staff has been in flux for the past month as the Beavers have auditioned for roles in the rotation.

Heimlich and Fehmel are both expected to get a start during the double-elimination baseball regional at Goss Stadium, but when they pitch will likely be kept a secret until the lineup card is finalized. Casey said freshman Kevin Abel is his third starter, but the Beavers have gone quickly to the bullpen in recent outings started by anyone other than Heimlich or Fehmel.

Oregon State (44-10-1), the No. 3 overall seed in the postseason, could call on Heimlich for his usual Friday start when it opens the regional at 7 p.m. against Northwestern State (37-22), the Southland Conference Tournament champion. Casey could also elect to save Heimlich for a possible showdown with LSU on Saturday and go with Fehmel or Abel against the Demons.

It would be risky to go with Abel (3-1, 4.13 ERA) in the opener, but Oregon State should give its starter a cushion with an offense that ranks among the top 10 in the nation with a .318 batting average and 7.5 runs per game.

Heimlich and Fehmel are a combined 23-2 and led the Beavers to a win in each of their past four starts. OSU is 0-3-1 during its past four series finales with Abel, Nathan Burns and Grant Gambrell all getting at least one start during that span while the Beavers allowed an average of seven runs in those games.

"We have had a little trouble there on that last day," Casey said. "We hope to have Abel as our No. 3 starter and certainly we have options there. (Christian) Chamberlain has had some good starts for us, but I'd like to think the three starters would be Luke and Bryce and Kevin if we could."

Chamberlain (2-0, 4.03 ERA), a freshman left-hander, threw 3 1/3 scoreless innings in his last start against San Diego two weeks ago. Gambrell (5-1, 4.40) was OSU's Sunday starter for most of the season.

Oregon State has been strong at the back of the bullpen with Jake Mulholland (1-2, 2.50), Brandon Eisert (4-3, 2.81) and Dylan Pearce (2-0, 3.81).

"We've got a little bit of a mixed bag out of the bullpen with some good and some not so good," Casey said. "We have to get a little more consistency out of our bullpen and do a better job."

Northwestern State will likely throw its ace, Ridge Heisler (7-2, 3.01), against the Beavers.

"Our coaching staff does a great job with reports to get us ready for whoever we might face," OSU second baseman Nick Madrigal said. "We will prepare like we have all season long."

LSU (37-25) and San Diego State (39-19) will precede the Beavers and Demons at 1 p.m. with the winners of each game facing off at 7 p.m. Saturday.

"You try to get as much film as you can, obviously there is a lot more television for LSU than for someone not in a Power 5 conference," Casey said. "You can call people that teams played, look for games that were streamed and talk to scouts, things like that."

Oregon State is hosting a regional for the seventh time since 2005 and went undefeated to reach the super regionals in five of the previous seasons including last year. The Beavers are 18-2 in regionals at Goss Stadium with the only losses coming to UC Irvine in 2014.