Even though he didn’t lose a single game Saturday, Nick Forester has some things that he wants to focus on before the Maine Principals’ Association’s state singles tennis semifinals and final on Monday.

Forester’s mental preparation may be a bit compromised on Sunday night, though. The top seed from Falmouth is a big Boston Celtics fan, and Game 7 of the Eastern Conference finals could go well past bed time.

“I’m not sure I will be able to stay up for it,” Forester lamented after cruising to 6-0, 6-0 wins in the Round of 16 and quarterfinals Saturday at The Racket and Fitness Center.

Girls’ No. 1 seed Rosemary Campanella of Kennebunk/Wells also advanced. The semifinals and finals are scheduled for Monday at Bates College in Lewiston but would move to The Racket and Fitness Center in the event of rain.

The semifinals will start at 9:30 a.m.

Rain forced Saturday’s slate indoors, flipping conditions for competitors who played in the heat and wind at Deering Oaks on Friday.

“It was much different (Friday),” said Forester, clad in a green Celtics T-shirt. “It was really windy and warm. I think today’s conditions were more favorable for everyone. I don’t think anyone was able to play their best tennis (Friday).”

Forester, who ousted unseeded Dennis Stewart of Bangor in the Round of 16 and No. 9 Quinn Clarke of Portland in the quarterfinals, said he will need to make some corrections to be playing his best Monday.

“I had too many unforced errors from behind the baseline and I want to shore up my volleys a little bit,” he said. “I’d like a higher first-hit percentage. Overall, though, I didn’t make too many mistakes today. I just want to be more solid (on Monday).”

Awaiting Forester in the semis is Mt. Ararat’s Peter Mao, the fourth seed who overcame back problems to defeat fifth-seeded Thorne Kieffer of Waynflete, 6-4, 4-6, 6-4, in the quarterfinals.

“I had a bit of tightness that I started really feeling about halfway through the second set,” Mao said. “It felt better after the medical timeout. I just had to stick with it and not fall into making long points.”

The other boys’ semifinal will pit Forester’s Falmouth teammate, third-seeded Alex Klemperer, against No. 7 Jacob Greene of Waynflete.

Klemperer took down unseeded Clay Canterbury of Freeport, 6-0, 6-4, in the Round of 16, then defeated No. 6 Parker Deprey of Caribou, 6-3, 6-3.

Greene defeated unseeded Matthew Ray of Falmouth, 7-5, 6-0, then upset second-seeded Declan Archer of Kennebunk/Wells, 6-2, 4-6, 6-4.

Archer’s day started earlier than most others, as he had to complete his second-round match against unseeded Dana Hinchliffe of Portland, which was suspended one game into the second set because of darkness Friday. Archer won, 6-2, 6-4.

Campanella, a senior, is seeking her third appearance in the final and her first state title.

“I think the important thing for Monday is just that I go into my match prepared,” Campanella said. “My goal is to just play my best tennis on Monday and to expect my opponents to play their best tennis going into the match.”

Campanella cruised through both of her matches Saturday, defeating unseeded Katrina Mason of Carrabec and ninth-seeded Abby Svor of Lewiston by identical 6-0, 6-0 scores.

In the semifinals, she will meet 12th-seeded Jocelyn Bolt of Gorham, who outlast fifth-seeded Meredith Kelley of Falmouth, 6-7 (4), 6-4, 6-4, then had an easier time in the quarterfinals against No. 4 Gabrielle Marquis of Caribou, 6-3, 6-1.

Campanella’s younger sister, Grace, will meet No. 6 Caitlin Cass of Lincoln Academy in the other semifinal.

Grace Campanella, the No. 2 seed, eliminated Anna Parker of Brunswick, 6-0, 6-0, and No. 10 Anastasia Kapothanasis of Cheverus, 6-1, 6-0.

Cass defeated No. 11 Ashley Matlock of Caribou, 6-1, 6-2, then upset No. 3 Izzy Evans of Greely, 7-5, 3-6, 7-5.

BASEBALL

THORNTON ACADEMY 5, MASSABESIC 4: Brogan Searle-Belanger’s RBI single in the eighth inning gave the Trojans (9-6) a win over the Mustangs (2-13) in Saco.

Cameron Seymour doubled and drove in two runs for the Trojans. Luke Chessie added two hits and an RBI.

Braden Daigneault doubled and drove in a run for Massabesic, and Nick Roberge had two RBI.

WINDHAM 10, WESTBROOK 0: Tanner Bernier threw a two-hitter, striking out nine, and the Eagles (10-5) scored eight runs in the fourth inning to get past the Blue Blazes (1-14) in six innings at Windham.

Bernier also doubled and scored three times. Bryce Afthim drove in two runs with a single and a triple, and Ryan Sargent had three hits.

Justin Copetta and Liam Coolidge got the Westbrook hits.

BIDDEFORD 4, SCARBOROUGH 3: Owen Sullivan pitched a five-hitter, and the Tigers (10-5) scored all their runs in the third inning as they beat the Red Storm (6-10) in Biddeford.

Kurtis Edgerton hit a run-scoring double, and Brice Springer and Tucker Dineen each added an RBI single. Evan Paquette’s sacrifice fly later in the inning made it 4-2.

FALMOUTH 4, SANFORD 0: Griffin Aube homered and pitched a five-hitter with 12 strikeouts to lead the Yachtsmen (8-7) past the Spartans (5-10) in Sanford.

Garrett Tracy and Connor Coffin each contributed two hits for Falmouth.

Marcus Gould had two hits for Sanford.

CHEVERUS 10, MARSHWOOD 0: Justin Ray struck out seven and Nathaniel Lapoint had three RBI to lead the Stags (10-5) to a five-inning win over the Hawks (8-7) in Portland.

Cheverus scored five runs in the third inning to take a 6-0 lead. Chris Cimino had two hits and two RBI, and Maxx St. John added two hits, an RBI and two runs scored.