DIXFIELD — In the playoffs, there is little margin for error. Dirigo didn’t make many Friday, dominated both sides of the ball in its Class D South quarterfinal football showdown with Old Orchard Beach, and came away with a 29-8 win at chilly Harlow Park.

Quarterback Riley Robinson ran for four touchdowns, gaining 177 yards behind a hard-blocking offensive line.

No. 2 Dirigo will host a regional semifinal next Friday night against the winner of Saturday’s game between Lisbon and Boothbay.

The offensive game plan work to perfection on the opening drive, a 10-play, 67-yard effort with Robinson scoring from the 2 on third down. Gus Brown kicked the point after for a 7-0 lead with 6:07 left in the first quarter.

“OOB is a good team,” said Robinson, who threw for three touchdowns to three different receivers in a 36-14 win against Old Orchard Beach last month. “We respect coach (Dean) Plante and his team, but our team is not looking past anybody at this point.”

Dirigo (7-2) struck quickly in its sixth consecutive win, scoring 15 points in the second quarter. It began with Bryce Whittemore blocking a punt for a safety.

Old Orchard kicked the ball and Dirigo returned it to the 44. Four plays later, Robinson followed the blockers for a 14-yard TD. OOB felt it slipping away and went to the air, but QB Dylan Boudreau threw it into Robinson’s hands and the Cougars were back in business.

Robinson ran in a 29-yard TD and Brown’s PAT made it 22-0 with 4:48 left in the half.

“We wanted to spread the field out,” Robinson said. “We wanted to run off tackle, and Quentin Penley and Isaac White did an excellent job. The team was inspired tonight, and we came out of here with the win.”

Dirigo had 273 yards on the ground, with Vincent Hebert (35 yards, 7 carries), Gavin Arsenault, Cooper Chiasson, Mike Casey, Cam Turner and freshman Alex Gorham adding to the total.

The Dirigo defense pressured the Seagulls throughout the game. Boudreau and Dylan Creswell combined for 7-of-15 passing for 49 yards. The Seagulls drove to the Dirigo 32 yard line, but Cam Turner intercepted the ball.

“A key for us defensively was swarming after the ball,” said Cougars end Cooper Chiasson, who had eight tackles and a sack.

Gavin Arsenault had his fourth interception in the past two games.

OOB (2-6) drove into Cougars territory on the opening drive of the second half, but, the defense stiffened and held firm on fourth down.

On second down, Robinson went off tackle again and sprinted 70 yards for a TD.

“It was important for us to start out fast,” Chiasson said. “Getting an early lead gave us plenty of momentum, and we followed through.”

In the fourth quarter, the Seagulls’ Erik Hogan broke free for 57 yards, but Arsenault ran him down.