Wylie had been cruising through the 9-6A schedule without a blemish on its record.
Sachse, on the other hand, endured some early struggles, and sat at 3-4 at one point.
But the Mustangs turned it up as the season progressed, embarking on a winning streak and that continued on Tuesday in handing the Pirates their first district loss.
Sachse ran its winning streak to six games in a row with a 3-1 victory as it clinched a spot in the playoffs.
The Mustangs (9-4) are tied for third place with Naaman Forest (9-4), one game behind Rowlett (10-3) in the standings.
Carson Sowell pitched 5.1 strong innings, giving up two hits and striking out six, with Jason Scrantom coming on in relief for the final 1.2 frames.
Runs were hard to come by for both teams, but Sachse made the most of its chances.
In the bottom of the third inning, Davis Tea doubled, moved over on a base hit by Jesse Ponce and scored on a ground out by Chris Marcellus to take a 1-0 lead.
In the fourth, Kyle Stanners reached on an error and eventually came around to score on a ground out by Tea to make it 2-0.
The Mustangs built on their advantage in the fifth, as Marcellus singled and Nathan Darden followed with a RBI double.
Wylie (12-1) made things interesting in the top of the seventh. Canyon Hall singled, and then with two outs, Cam Pruitt walked and Logan Jeske delivered a RBI double to close to within 3-1. Luke Wiseman walked to load the bases but Scrantom was able to slam the door on the rally.
Rowlett got a strong outing on the mound from Jaxon Kirkhuff and used a pair of big innings to pull away for a 11-5 victory over Garland to remain in sole possession of second place.
After two scoreless frames, Rowlett got the offense going in the top of the third inning.
Garrett Gibbs singled, moved to second on a wild pitch and scored on a base hit by Hudson Parker to take a 1-0 lead.
Later in the inning, Anthony Valenzuela beat out a potential double-play ball, allowing Emilio Luna to score to make it 2-0.
Although out of the playoff race, Garland did not go down without a fight, as Anthoney singled home a run in the bottom of the third and another run scored on a wild pitch to tie it at 2-2.
Rowlett had an instant response in the top of the fourth with a five-run rally.
Chris Collins singled, Christian Cuevas was hit by a pitch and Zach York reached on a bunt single to load the bases with nobody out.
Gibbs then drove in a run on a bunt single, two runs scored when Parker’s hard ground ball to shortstop was mishandled and Luna delivered the big blow with a two-run triple to left to push the lead to 7-2.
The Owls scratched across a run in the bottom of the fourth inning, but the Eagles continued to match them.
In the top of the fifth, Jaxon Kirkhuff reached on an error and came around to score on a sacrifice fly by Cuevas, and in the sixth, Heath Salyards, Kirkhuff and Collins all drove in runs to extend the advantage to 11-3 and that would be more than enough for Kirkhuff to close it out, as he went the distance, striking out six and allowing just two earned runs in seven innings.
Naaman Forest, who is also playoff-bound, remained in a tie for third place with a 5-1 win over Lakeview (6-7). Alex Davila struck out 10 and allowed just three hits in six innings, with Jaden Flores coming on to close it out, fanning two of the three batters he faced.
The Rangers struck in the third inning when Jason Flores doubled and scored on a base hit by Ben Allan and Jaden Flores delivered a two-run triple.
Naaman Forest added some insurance in the seventh, as Jaden Flores had a RBI double and Jacob Khong followed with a run-scoring triple.
North Garland notched its second district win with a 11-8 victory over South Garland.
Agustin Valenciana struck out eight in 5.1 innings and went 2-for-2 with two runs batted in. Frankie Tolbert was 3-for-4 with two runs scored and one driven in, Derrick Williams doubled, tripled and scored twice and Sammy Canales added a pair of RBIs.
Luis Barco went 2-for-5 with two runs and four RBIs and Tyler Mowatt also plated a pair of runs for the Titans.
Rowlett will try to secure the second seed in the playoffs when it hosts Lakeview on Friday. Naaman Forest hosts Sachse, with the winner edging ahead in the standings.