It's hot in Arizona and it's not about the 100-plus-degree temperature.

Hawai'i will face sizzling San Diego in today's opener of the NCAA Tempe, Ariz., Regional at Packard Stadium on the Arizona State campus.

Game time is 11 a.m., Hawai'i time.

In the other opener, host and national top seed ASU will play Wisconsin-Milwaukee.

The Western Athletic Conference champion Rainbows (33-26) will take on the West Coast Conference champion Toreros (36-20), winners of 22 of their last 30.

The Rainbows won a March 29 meeting in San Diego, 8-6, on the strength of a Christian Johnson grand slam. But that was under different circumstances. The Rainbows made about a 90-minute drive from Orange County to San Diego for a Monday game.

Meanwhile, the Toreros had just returned from taking 2 of 3 in a weekend series at Coastal Carolina. Hawai'i used Zach Gallagher, who pitched six innings. Jet-lagged San Diego staffed the game with six pitchers.

"They're a great club," UH coach Mike Trapasso said. "We can't take anything away from the last time we saw them. We're totally different teams, both of us. They are as hot a team there is in the country right now."

Matt Sisto (5-5, 5.57 ERA) will start today for the Rainbows. Josh Slaats (5-3, 3.22) will start tomorrow. Sisto last pitched May 28, when he went seven innings to beat Fresno State, 11-3. Sam Spangler (5-6, 4.42), who pitched 3 1/3 innings of relief in Sunday's WAC title game, is scheduled to start Sunday.

The Toreros may be hot, but the Rainbows are warming up. They enter the Regional having won 12 of their last 16.

They may have bolstered the bench with the improving health of Johnson, who will be available to pinch hit.

"He's swinging better," Trapasso said. "He may have a chance to get some at-bats this weekend because he's swinging better and he's getting some bat speed back."

The left-handed hitting Johnson hasn't played since dislocating his right shoulder and tearing his labrum April 16, when he attempted a diving catch of a foul fly against Sacramento State.

Joining the team is reserve first baseman Easton Torigoe. He replaced Derek Brown, who wanted to get started with summer ball. Brown, a freshman walk-on, will not return next season, Trapasso said.

San Diego had not announced a starting pitcher as of yesterday. No matter, as any of its three starters, right-handers Kyle Blair and AJ Griffin, and left-hander Sammy Solis are draft prospects. Blair is the WCC Pitcher of the Year.

"I'd imagine we'll see Blair or Solis," Trapasso said. "Both are outstanding."

San Diego outfielder James Meador (.391, 7 HR, 62 RBI) was named WCC Player of the Year for the second consecutive season.

TODAY’S OTHER REGIONALS

At Norwich, Conn.

Central Connecticut State (33-21) vs. Florida State (42-17); Oregon (38-22) vs. Connecticut (47-14)

At Charlottesville, Va.

Virginia Commonwealth (34-24-1) at Virginia (47-11); St. John's (40-18) vs. Mississippi (38-22)

At Louisville, Ky.

Illinois St. (31-22) vs. Vanderbilt (41-17); Saint Louis (33-27) at Louisville (48-12)

At Columbia, S.C.

The Citadel (42-20) vs. Virginia Tech (38-20); Bucknell (25-33) at South Carolina (43-15)

At Myrtle Beach, S.C.

Stony Brook (29-25) vs. Coastal Carolina (51-7); N.C. State (38-22) vs. College of Charleston (42-17)

At Atlanta

Elon (38-22) at Alabama (37-22): Mercer (37-22) at Georgia Tech (45-13)

At Gainesville, Fla.

Oregon State (31-22) vs. Florida Atlantic (35-22); Bethune-Cookman (35-20) at Florida (42-15)

At Coral Gables, Fla.

Florida International (36-23) vs. Texas A&M (40-19-1); Dartmouth (26-17) at Miami (40-17)

At Auburn, Ala.

Southern Mississippi (35-22) vs. Clemson (38-21); Jacksonville State (32-24) vs. Auburn (40-19)

At Fayetteville, Ark.

Grambling State (22-30) at Arkansas (40-18); Kansas State (36-20) vs. Washington State (34-20)

At Norman, Okla.

Oral Roberts (35-25) at Oklahoma (44-15); North Carolina (36-20) vs. California (29-23)

At Austin, Texas

Louisiana-Lafayette (37-20) vs. Rice (38-21); Rider (36-21) at Texas (46-11)

At Fort Worth, Texas

Arizona (33-22) vs. Baylor (34-22); Lamar (35-24) at TCU (46-11)

At Fullerton, Calif.

New Mexico (37-20) vs. Stanford (31-23); Minnesota (30-28) at Cal State Fullerton (41-15)

At Los Angeles

UC Irvine (37-19) vs. LSU (40-20); Kent State (39-23) at UCLA (43-13)