A warning to the baseball teams seeded No. 1 in their respective South Jersey brackets: Don't be overconfident.

A year ago, none of the six South Jersey top seeds won NJSIAA sectional titles.

This year's South Jersey top seeds are Maple Shade in Group 1, Haddon Township in Group 2, Shawnee in Group 3, Toms River North in Group 4, Bishop Ahr in Non-Public A, and St. Rose in Non-Public B.

The public-school portion of the tournament starts today, with the second round being played Friday.

The Non-Public A competition begins Friday, while Non-Public B starts May 27.

Last year's sectional champs included 14th-seeded Washington Township (Group 4), 10th-seeded Sterling (Group 2) and ninth-seeded St. Joseph Metuchen (Non-Public A). The other champs were three fourth-seeded teams: Pennsville (Group 1), Seneca (Group 3) and Gloucester Catholic (Non-Public B).

For what it's worth, this year's No. 4 seeds are Penns Grove (Group 1), Overbrook (Group 2), Moorestown (Group 3), Winslow Township (Group 4), Christian Brothers Academy (Non-Public A), and Holy Cross (Non-Public B).

Dreamy matchups.

Two of the best early-round matchups are in Group 2: Today, streaking Gateway is at Haddonfield, and fifth-seeded Audubon will play at fourth-seeded Overbrook on Friday.

All are strong contenders in a wide-open field.

Gateway has won 10 of its last 11 games.

Colonial domination.

The Group 2 section looks a lot like the Colonial Conference. The 11-team section features six Colonial teams: top-seeded Haddon Township, third-seeded Collingswood, fifth-seeded Audubon, seventh-seeded Haddonfield, ninth-seeded Haddon Heights and 10th-seeded Gateway.

A seventh team, Overbrook, will leave the Tri-County Diamond and join the Colonial next season.

Pulling a "Washington Twp."

A year ago, Washington Township, despite being seeded 14th in the 15-team South Jersey field, won the Group 4 state title. This year's Group 4 field also has some interesting double-digit seeded teams, including 10th-seeded Mainland, 12th-seeded Cherokee, and 13th-seeded Cherry Hill East.

In one of the tournament's best openers, surging Cherokee will play at fifth-seeded Millville today. Millville is expected to throw its ace, Mike Trout, while Cherokee will use Gary Wilson (3-1) and lefty Dan Smith (5-1).

"Baseball's a simple game - it all comes down to pitching," Cherokee coach Bill Haessler said.

Lately, Cherokee has been getting very good pitching. Wilson missed two weeks after straining his back against Lenape last month. Since then, he has pitched in two games and thrown a total of eight scoreless innings.

"We're glad to have him back," Haessler said, "and while he was out, Danny picked up the slack."

Haessler, who is retiring after the season, does not want to overuse Wilson, so it's likely he and Smith will divide today's duties.

Notes.

Mainland righthander Charlie Law, a hard-throwing, 6-foot-7 senior who has signed with Rutgers, has been invited to personal tryouts by the Phillies, Yankees and Cardinals. . . . Penns Grove's Don Haines leads South Jersey with 11 homers. . . . Power-hitting shortstop Steve Bruno, a recent transfer from Philadelphia's St. Joseph's Prep, should help Gloucester Catholic's drive for its 20th sectional title and 14th state crown.

Contact staff writer Sam Carchidi at 215-854-5181 or scarchidi@phillynews.com.