PORTLAND, Ore. -- Pioneer clinched first place in Pool A of the Little League Softball World Series with a 6-3 victory over Tallmadge, Ohio, on Sunday night.Pioneer will play the Pool B runner-up in the semifinals at 7 p.m. Tuesday. The game will be on ESPN2.With Puerto Rico's loss to Oregon earlier in the day, Pioneer knew it had already clinched a berth in the semifinals. Ohio will play Puerto Rico on Monday for second place in Pool A."We knew tonight's game was a big one and that the winner would probably end up first in our pool," Pioneer coach Micky Mallory said. "We knew what was at stake."But first Pioneer will finish pool play with a game against the Czech Republic at 1 p.m. Monday. The game will be available on the internet on espn3.com. The Czech Republic is 0-3.In Sunday night's game, Pioneer broke a 1-1 tie by scoring three runs in the third for a 4-1 lead.Raelee Weaver led off by reaching on an error. She later scored on a passed ball. Kamdyn Fuller, who had reached on a fielder's choice, scored on Jada Chadwick's single.After Ohio scored twice in the top of the fourth to climb to within 4-3, Pioneer scored twice in the fifth to extend the lead back to three, 6-3.Fuller reached with a lead-off single and eventually moved to third base, where a low throw bounced off the bag and rolled to the fence, allowing her to continue home. Several batters later, Lindsey Sanders curved a shot into the right-field corner to extend the gap to 6-3.The three runs Ohio scored were the first runs scored off Weaver. She pitched back-to-back shutouts against Oregon and Puerto Rico.Ohio scored a run in the first. Weaver got out of a jam in the second inning. She got a ground out with two on and two outs.Weaver got out of an even-bigger jam in the third as Ohio loaded the bases with one out. But Weaver started a double play after fielding a grounder.Ohio loaded the bases again in the fourth. This time, it pushed across a pair of runs to climb to within one run at 4-3.Pioneer got on the scoreboard in the bottom of the second inning when Sammie Cotton led off with a walk. Kennedi Bedell followed with a bunt and opened the doorfor Cotton when she stole second base.The catcher tried for the out, but the moment the ball left her hand Cotton sprinted home.Savannah Lundrum connected on a sacrifice fly that brought Bedell home for a 2-1 lead that the team would never surrender."These girls know how to play with their backs to the wall, so coming back from one run is nothing for them," Mallory said.-- Kevin Price contributed to this report.