In this Mets’ season headed sideways, Jacob deGrom represents a glimmer of hope. One of the best starting pitchers in baseball over the past several years, he has taken his work on the mound to another level this season. Even against the juggernaut of the Yankees lineup, deGrom was a capable foe.

For seven stout innings on Friday, in the opener of this year’s first Subway Series, deGrom efficiently limited the Yankees’ powerful bats. But with no room for error because of the Mets’ inept offense, one mistake by deGrom can mean the game.

And when DeGrom hung a changeup in the eighth inning, the pesky right fielder Brett Gardner smashed it for a tiebreaking two-run home run. A blank expression on his face, deGrom watched the ball fly over the right-field fence and then hunched over at the waist. Gardner celebrated in the dugout in what would become a 4-1 Yankees win.

“He’s one of the best pitchers in the game, man,” Gardner said. “He could be efficient against an All-Star team for 10 starts in a row.”

Masahiro Tanaka, the Yankees’ starter, had a rough moment, too. But it meant only an early shower, not a loss.

Interleague play in a National League stadium brings complications for American League teams. Despite swinging a hot bat, outfielder Aaron Hicks sat on Friday because the Yankees lost the use of the designated hitter. Tanaka had to hit and run the bases, and it ended up hurting him.

Tanaka reached base on a fielding error in the top of the sixth by the normally sure-handed first baseman Adrian Gonzalez. Tanaka ran to second base on a single by Gleyber Torres, and took his time going to third when Gardner walked to load the bases.

The Yankees tied the score, 1-1, when Tanaka went home on a sacrifice fly by Aaron Judge. A two-hop throw to the other side of home plate from right fielder Jay Bruce allowed the slow-footed Tanaka to score.

But the trip home strained Tanaka’s legs, and he had to leave the game with stiff hamstrings.

He said later that he had felt the discomfort running home. Yankees Manager Aaron Boone said Tanaka had received intravenous fluids and would be re-evaluated on Saturday.

The Mets, in the midst of a seven-game losing streak, have tied a franchise record by scoring one run or fewer in five straight games. Their starting pitchers have a 2.35 earned run average over the past 19 games, but the Mets are 5-14 in that span.

DeGrom has a 1.30 E.R.A. over his past nine starts, and the Mets have won just two of those games.

Brandon Nimmo, the Mets’ left fielder, homered in the first inning on the second pitch he saw.

“They basically pitched a shutout after the first run,” Mets Manager Mickey Callaway said.

Then came the fateful eighth inning. DeGrom coughed up a second single to Torres, and then two pitches later the home run to Gardner.

“One swing can hurt us and cost us the game, and that’s a tough way to go out and pitch every night,” Callaway said. “Even when you throw a nine or 10-pitch inning, it’s kind of a stressful inning because the score is so close.”

After the game, deGrom insisted the losses in good performances were not wearing on him.

“My goal is to go out there and put up zeros,” he said.

Added Mets third baseman Todd Frazier: “I feel for him, man. We’re trying but just not producing at the place. Gives up three runs and we’ve got to win those games.”

In the ninth inning, Yankees left fielder Giancarlo Stanton added a solo home run off Paul Sewald.

Earlier in the day, the Mets placed closer Jeurys Familia on the disabled list because of soreness in his throwing shoulder that he complained about after his outing on Wednesday. Callaway said Familia’s magnetic resonance imaging examination was “pretty clean.”

The Mets also announced that starting pitcher Noah Syndergaard, who has a strained ligament in the index finger of his throwing hand, would not return from the disabled list as planned on Sunday to face the Yankees. Seth Lugo will replace him.

After the game, Cespedes told reporters through an interpreter that he expected to come off the disabled list on Tuesday in Atlanta, but he also delivered some brutally honest comments that may raise eyebrows in Flushing.

“For the way the team is playing right now, even if I’m doing very well, if the team remains playing this way, I don’t think it’s going to help,” he said. “But I’m eager to get back.”