SACO — During warm-ups, Oxford United players casually adjusted the heart monitors beneath their bright yellow jerseys. The equipment and the attitude were evidence of the routine science that professional English soccer clubs bring to the opening weeks of preseason training.

At the other end of the field, no monitors were necessary. You could almost hear the hearts pounding.

But after some initial jitters, the semiprofessional Seacoast Mariners, comprised entirely of Maine players, held their own as English League Two side Oxford United held on for a 2-1 exhibition win Tuesday night before a crowd of about 600 at Thornton Academy.

“That was an awesome experience,” said Mariners defender Ben Brewster of Cape Elizabeth and Bowdoin College. “They’re big, fast and technical. After that first 10 minutes, I thought we settled in and played with them the rest of the way.”

The U’s came out confident, taking advantage of the space the Mariners provided to string together 8 to 10 passes at a time. Seacoast found its way into the game, making hard tackles and challenging for 50-50 balls.

“It’s an early game for us and it’s always competitive playing American teams,” said Oxford Manager Chris Wilder. “We’re a little disappointed we didn’t convert more of our chances and the goal we conceded was a little bit sloppy, but now we can look forward to the next game.”

United went ahead 1-0 in the 40th minute when Deane Smalley beat former Gorham and St. Joseph’s goalie Will Pike on a penalty kick.

At halftime, about 200 youth players poured onto the field for “a kick-about,” part of the festive atmosphere of the U’s three-game U.S. tour celebrating the partnership between Oxford and Seacoast, which is based in New Hampshire and Maine.

Meanwhile the Mariners plotted the second half.

“They controlled the first half quite a bit, but being down 1-0, we had a sense that we could put one away in the first five minutes,” Brewster said. “To see that confidence was awesome.”

Forward Eddie Jones of Scarborough and Bowdoin expressed that confidence, spinning past his mark twice on one run along the left wing and later putting a few hard shots on the U’s Ryan Clarke.

“It was a great competitive game for Maine soccer,” Jones said. “It was a lot faster than what we’ve seen this summer. But we settled down and played our game.”

Sean Rigg put the U’s up 2-0 in the 83rd minute, beating a diving Peter Morrell of Brunswick and Williams College.

Nick George of Bangor and Maine Maritime got one back for Seacoast, finishing off a left-footed cross from Gabe Warren (Edgecomb/Maine Maritime) in the corner. The play was set up by former Greely and Brown forward Iain Eldridge, who read Warren’s overlap and slipped him the ball along the left touchline.

Oxford heads to New Hampshire for a game Friday night in Portsmouth against Seacoast’s Premier Development League team, the Phantoms. Most of the Mariners head off to their college preseason camps in a few weeks. And many in the stands head home having seen English professionals in Maine.

“It was a great experience for the players, the club and soccer in Maine,” said Seacoast Coach Peter Mills. “At halftime, to see all those kids out on the field was great. It kind of made you think that someday they’ll be playing in a game like this too.”