North Allegheny was the only defending champion to draw a No. 1 seed Friday when the WPIAL released brackets for the upcoming baseball playoffs.

The Tigers were seeded first in Class 6A. The other top seeds went to Pine-Richland in 5A, Indiana in 4A, Riverside in 3A, Neshannock in 2A and Serra Catholic in A.

The playoffs begin Tuesday with first-round games in Class A, 2A and 3A.

Class 4A and 5A start play Wednesday while the Class 6A bracket begins May 19.

The championship games are May 27-28 at EQT Park in Washington.

Class 6A

Quarterfinals

May 19 schedule

Times, sites TBA

Hempfield (8-12) vs. North Allegheny (13-6)

Butler (10-8) vs. Norwin (12-8)

North Hills (7-12) vs. Canon-McMillan (14-6)

Mt. Lebanon (8-12) vs Seneca Valley (13-6)

Class 5A

First round

Wednesday’s schedule

Trinity (10-8) vs. Pine-Richland (17-3) at Plum, 6:30 p.m.

Latrobe (14-6) vs. Fox Chapel (14-5) at Gateway, 7 p.m.

Franklin Regional (10-7) vs. Bethel Park (16-4) at Boyce Mayview Park, 7 p.m.

Upper St. Clair (13-6) vs. Thomas Jefferson (14-4) at West Mifflin, 7 p.m.

Mars (8-10) vs. Plum (18-2) at Fox Chapel, 3 p.m.

Baldwin (9-7) vs. Peters Township (13-6) at Boyce Mayview Park, 4:30 p.m.

Montour (12-7) vs. Shaler (13-6) at North Allegheny, 7 p.m.

Connellsville (13-5) vs. Penn-Trafford (14-6) at Norwin, 4 p.m.

Class 4A

First round

Wednesday’s schedule

Ambridge (8-10) vs. Knoch (10-10) at North Allegheny, 4 p.m.

Derry (5-9) vs. Belle Vernon (13-5) at Gateway, 4 p.m.

Greensburg Salem (9-6) vs. Central Valley (10-9) at Seneca Valley, 6 p.m.

Ringgold (10-9) vs. Blackhawk (10-7) at West Mifflin, 4:30 p.m.

Byes: Indiana (18-1), West MIfflin (15-5), Elizabeth Forward (13-3), Beaver (11-8)

Class 3A

Preliminary round

Monday’s schedule

McGuffey (10-9) vs. Shady Side Academy (7-12) at West Mifflin, 5 p.m.

Keystone Oaks (8-9) vs. South Allegheny (7-9) at West Mifflin, 7:30 p.m.

First round

Tuesday’s schedule

McGuffey/Shady Side Academy vs. Riverside (13-2) at Seneca Valley, 6 p.m.

Charleroi (10-6) vs. Burrell (12-8) at Gateway, 3 p.m.

Freeport (13-6) vs. Waynesburg (15-3) at Gateway, 5:30 p.m.

Mt. Pleasant (12-6) vs. South Park (12-6) at Gateway, 8 p.m.

Keystone Oaks/South Allegheny vs. Avonworth (17-3) at Fox Chapel, 4:30 p.m.

Ligonier Valley (10-7) vs. Quaker Valley (12-6) at Fox Chapel, 2 p.m.

Seton LaSalle (10-6) vs. Ellwood City (14-5) at North Allegheny, 7 p.m.

Mohawk (10-8) vs. Deer Lakes (9-6) at North Allegheny, 4 p.m.

Class 2A

First round

Tuesday’s schedule

Apollo-Ridge (8-7) vs. Freedom (11-7) at Plum, 7:30 p.m.

Chartiers-Houston (7-9) vs. Shenango (14-5) at Burkett Park, 4 p.m.

Laurel (8-10) vs. Fort Cherry (13-5) at Shaler, 2 p.m.

New Brighton (9-8) vs. South Side (11-6) at Shaler, 4:30 p.m.

California (8-9) vs. Riverview (12-5) at Norwin, 4:30 p.m.

Bye: Neshannock (15-4), OLSH (13-7), Burgettstown (12-3)

Class A

First round

Tuesday’s schedule

Winchester Thurston (11-6) vs. Jefferson-Morgan (13-3) at Norwin, 2 p.m.

Rochester (9-7) vs. Bishop Canevin (10-6) at Burkett Park, 6:30 p.m.

Sewickley Academy (5-11) vs. Greensburg Central Catholic (14-2) at Plum, 5 p.m.

Avella (10-7) vs. Western Beaver (14-4) at Boyce Mayview Park, 3 p.m.

Union (7-9) vs. Carmichaels (12-4) at Boyce Mayview Park, 5:30 p.m.

Bye: Serra Catholic (16-3), Eden Christian (13-4), Leechburg (14-3)