The Gaels (1-1) held 6-foot-7 forward Chris Kurz to just four points - all in the first half - and forced him out of the game with five fouls in the final seconds.
"(Logan) Bolinger, Mitch (Belella) and (Evan) Henderson did a heck of a job on (Kurz)," Robertson said. "In the last half of the game, we went to a combo defense to stop him."
Meanwhile, Penn Charter (0-2) had a much tougher time defending John Duhring, Goretti's tallest force at 6-5. Duhring held his own inside the paint despite facing bigger competition and posted a double-double with 15 points and 10 rebounds.
"It was rough, but I just had to try to get position and box out," said Duhring, who had five offensive boards. "We just had to work hard for the whole game."
The Gaels had a nine-point lead at the start of the third quarter, but watched it slowly slip away as Penn Charter's Sam Zeglinski began to heat up. Zeglinski, who had just four points at halftime, hit two 3s and scored 12 points in the third as the Quakers took their first lead of the game. A 3 by Mike Brown put Penn Charter ahead 49-47 heading into the fourth quarter.
Goretti's Kevin Breslin, who led the team with 23 points, was held scoreless in the third as the Gaels were outscored 24-13.
"We struggled a little in the third quarter. We just had to get back on our game," Breslin said.
The Quakers extended the lead to as many as four points at the start of the fourth quarter, just before the Gaels began to claw back.
Trailing 58-55 with about 4 1/2 minutes left, Breslin and Bolinger hit back-to-back shots to give Goretti its first lead since late in the third quarter.
Penn Charter got the lead back on a pair of foul shots by Brian Teuber, but the free-throw advantage belonged to the Gaels. Two free throws by Benny Alencherry gave Goretti a 61-60 lead, which it protected down the stretch.
The Gaels refused to give Penn Charter an open shot and were in place for the defensive rebounds to keep the Quakers from cutting into the lead. That forced the Quakers to send Goretti to the charity stripe 12 times in the final 1:10 and the Gaels hit 11, including the front end of three 1-and-1s.
Alencherry hit two of the front ends and was 10-for-10 from the line with 14 points.
"This was a good effort all around, by the whole team," Robertson said. "If we don't get what we had from each of these guys, we probably don't win."
Penn Charter hit two baskets in the last four seconds of the game, including a 3 at the buzzer. Zeglinski had a team-high 19 points, Travis Robinson had 15 and Leland O'Connor had 11.