WESTFORD — When the bracket for the Div. 1 girls tennis tourney came out, Newton South coach Noura Guermazi cracked a bit of a smile seeing Westford Academy as a potential quarterfinal opponent.

And wouldn’t you know it, on Sunday at the WestFit Fitness Center, that was the matchup on the agenda. And like the first time the teams played this season, it came down to a final match.

This time, however, it was the Lions who flipped the script on Westford as Manel Guermazi outlasted Nina Chawla, 6-4, in a third and deciding set to clinch a 3-2 Newton South win and a date in the semifinals with Boston Latin on Tuesday in Lexington.

“We really expected a match like this,” said Guermazi, Manel’s mother. “Westford has so many talented players, but we really wanted to have another chance to play them after the first match.”

It felt like it was going to come down to a final match for most of the afternoon. The Grey Ghosts scored the first point of the day with Melanie Chang’s straight set win at third singles over Julia Arbuleda.

Newton South tied things up when the sister team of Julia and Lauren Sayers scored a 6-2, 7-5 win in first doubles. But Westford retook the lead when Ambika Arunrajesh and Haasini Paparaju won 6-4, 6-4 at second doubles.

That turned all the attention to the final two singles matches on court where it looked like Westford might find the decisive point after Emily Chan beat Olivia Whitaker handily in the first set. But Whitaker rebounded for a 6-4 win in set two that saw her rally from a 4-1 hole and bolted to a 4-1 lead in the final set before Chan ripped off the next three games to even things up.

Whitaker, however, came up with two huge winners to hold for a 5-4 lead and then broke Chan in the next game to win 6-4 and tie the match at 2-2.

“Olivia did a great job of turning her match around,” Guermazi said. “Her body language in the first set wasn’t so good but once she got that settled, she really started playing better.”

That decision turned all the focus on to second singles where Chawla and Manel Guermazi had split the first two sets.

The third set also was a back-and-forth affair until Guermazi won back-to-back games to take the lead and then was able to break Chawla’s serve to seal the match and the win.