TEMPE, Ariz. » The mystery surrounding Hawaii's starting pitcher will have to wait another day.

Coach Mike Trapasso said after practice at Hohokam Park in Mesa, Ariz., yesterday that he still hadn't decided whether junior Josh Slaats or sophomore Matt Sisto will start Hawaii's first NCAA tournament game in four years.

The Rainbows (33-26) begin play in the Tempe regional tomorrow at 11 a.m. against San Diego (36-20).

“;The main thing is just seeing how Slaats feels,”; Trapasso said. “;He's gone four days, three days and now four days rest so we'll wait and see if he wants another day's rest.

I know he's going to want the ball, but he'll pitch either Friday or Saturday.”;

Slaats started last Wednesday against Louisiana Tech on four days' rest and allowed no earned runs in 5 2/3 innings, throwing 89 pitches. He came back on Sunday and threw 56 pitches in three innings of Hawaii's win over Fresno State to claim its first Western Athletic Conference tournament championship since 1992.

Sisto came up with a clutch performance against the Bulldogs on Friday, allowing two runs in seven innings.

Whoever gets the start could have the support of senior Christian Johnson, who looks ready to contribute this weekend.

Johnson hasn't played since dislocating his shoulder in the series at Sacramento State in mid-April. He was hitting .533 (8-for-15) in WAC play with three home runs and five RBIs before the injury.

Johnson was the hero in Hawaii's 8-6 win over San Diego earlier this year, hitting a grand slam to offset two home runs by San Diego catcher Zach Kometani, a 2008 Punahou graduate.

“;He's going to be good to swing a little bit I think,”; Trapasso said. “;He's had to change his swing a little bit, keep the top hand on it, and it takes a little getting used to, but the main thing I'm looking at is the pain tolerance and the bat speed and both were there.”;

Johnson had as much pop as anyone in batting practice yesterday, hitting several thunderous bombs over the right-field fence at the practice field.

Sophomore first baseman Easton Torigoe was expected to join the team late last night and will be on the 27-man roster for the tournament.

Freshman Derek Brown left the team after Sunday's win over Fresno State and will not return next season, Trapasso said yesterday.

Brown, a 2009 graduate of Woodstock High School in Woodstock, Ill., appeared in three games this season. He started at first base against Stanford on May 18 and went 0-for-3. He finished 0-for-5 and allowed four hits and two runs in 1 1/3 innings against Southern California in his only appearance on the mound.

Torigoe hasn't played since late March, when Kevin Macdonald missed two games with a foot injury.

He had a memorable game against Air Force, hitting a grand slam for the first home run in his career.