As the scoreless innings piled up Tuesday afternoon in the first Maryland 4A semifinal, right-hander Chris Ruszin and the Chesapeake baseball team waited patiently for an opportunity.

In the sixth inning, they got five.

Chesapeake took advantage of five throwing errors by Gaithersburg, scoring four runs and riding Ruszin’s brilliant performance on the mound to a 6-0 victory at the University of Maryland’s Shipley Field.

The Cougars will return to the state championship game for the first time since 2010 in search of their first title since 1997. In a rematch of the 2010 title game, they will face Sherwood, which cruised past Eleanor Roosevelt, 10-0, in the second semifinal, at Ripken Stadium in Aberdeen on Friday night.

“We talked before the game, we just had to put the ball in play,” Ruszin said. “We always preach, ‘Play with a lead.’ Playing with a lead changes teams. Once we got the lead, they started throwing it around a little bit, and the rest is history.”

Gaithersburg’s errors allowed the Cougars to break the game open, but for five innings, Ruszin kept them in it. Less than a week after blanking Severna Park in the region semifinals, the Towson commit struck out seven and allowed just two hits in another shutout. He improved to 7-0 with a 0.64 ERA this season.

“Sometimes he has a tendency to amp up a little bit, a big strong kid, and he didn’t do that,” Coach Ken King said. “He kept in control, kept his fastball low and gave us a chance to make plays behind him.”

Ruszin shut down the Trojans (20-3), who boast one of the state’s most potent lineups, and kept pace with Virginia-bound left-hander Anthony Felitti, who didn’t allow an earned run over five-plus innings. The pitchers’ duel continued into the sixth, when Gaithersburg unraveled.

After John Drexel singled to lead off the inning, the Trojans committed three errors in the following two at-bats. Two walks, a pitching change and two more errors followed. When the inning finally came to an end, Chesapeake carried a 4-0 lead.

“It wasn’t physical. It was mental,” Gaithersburg Coach Jeff Rabberman said. “We kind of let the moment get to us. We let one error become two errors, two errors become three errors, and at this level, you can’t do that.”

The four-run cushion was more than enough for Ruszin, who benefited from solid outfield defense to seal the win for the Cougars (23-2).

“We have the best defense in the county, state — I’ll throw us out there against anybody,” he said. “We don’t beat ourselves very often.”

SHERWOOD 10, ELEANOR ROOSEVELT 0: Senior All-Met Matt Chanin threw the first no-hitter of his career and added 16 strikeouts for good measure, leading the Warriors to a rout of the Raiders in the second semifinal.

Chanin had at least two strikeouts in each of his seven innings and struck out Eleanor Roosevelt in order in the third and sixth. The UMBC commit overpowered the Raiders (17-4) with his fastball and kept them off-balance with a brutal slider. Coach Sean Davis said the right-hander’s performance was, “the best I’ve ever seen him throw.”

“Matt’s outing made life a little bit easier on us,” Davis said. “Early in the game, we weren’t really swinging the bats too well, but with the way he was throwing, we didn’t press.”

Each of Sherwood’s starters reached base at least once, led by senior center fielder Brady Adam, who went 3 for 4 with two doubles, a triple and four RBI.

One of his hits ricocheted off the net above straightaway center, and another cleared the first fence but did not clear the net and therefore was ruled a ground-rule double. Davis said Adam is in line to start the state championship game Friday night.

While other teams arrived at the state tournament with only a handful of losses, the Warriors (15-7) have endured several highs and lows throughout the season. They will face another test Friday against Chesapeake, the top team in Anne Arundel County.

“You’re going to battle, you’re going to lose momentum, you’re going to be down in games,” Chanin said. “You have to learn how to win.”

Poolesville falls in semifinal

Hunter Pearre singled to tie the game with two outs in the bottom of the seventh inning, but Poolesville ultimately succumbed in the ninth, losing 5-4 to Parkside of Wicomico County.

Poolesville quickly fell into a 3-0 hole and was trailing 4-1 entering the sixth, but the Falcons tacked on two runs to pull within 4-3 entering the seventh. Pearre drove in Robbie Metz to send the game into extra innings, where their best season in program history abruptly came to an end.

“It was a great baseball game,” Poolesville Coach Steve Orsini said. “We made too many mental mistakes. Parkside is very good.”

Thayer Seely led Poolesville (20-2), which was playing in its first state semifinal game, with a pair of doubles. He also gave up four runs over six innings, finishing with eight strikeouts and no walks.