WASHINGTON - For the second time this week, the Mets have reason to be concerned about closer Jenrry Mejia.

After their 5-3, 13-inning loss to the Nationals on Thursday, Mejia revealed that he has spent the last three days nursing soreness in his right calf. The issue flared up again as he navigated a scoreless 12th inning.

"It's not going to affect me [for] tomorrow," said Mejia, who played down the injury.

In his previous outing Monday, Mejia complained of stiffness in his lower back. Terry Collins hoped to avoid using Mejia altogether, just as he had the last few days, when he was given time off to rest his leg.

But when Mejia said he felt soreness, Collins resolved to cap his appearance at one inning. "The trainers, right now they don't think it's anything serious," Collins said. "But it's serious enough that he wasn't going to pitch anymore."

In a slide

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Carlos Torres extended what has been a miserable stretch by allowing Bryce Harper's walk-off two-run homer in the 13th.

Torres has been one of the Mets' most flexible arms in the bullpen, capable of spot starting. But he has surrendered a homer in four of his last five games.

"Right now, he's struggling about as bad as I've seen him," Collins said.

Lately, Torres said he has been burned by walks, which happened Thursday when he issued a free pass to Ian Desmond to set up Harper's winning blast.

In his last four outings, Torres has walked four in three innings, compiling a 15.00 ERA.

Extra bases

Nationals first baseman Adam LaRoche finished the three-game series 8-for-10 with two homers . . . Daniel Murphy went 3-for-3 against Jordan Zimmermann, upping his lifetime average against the righthander to 16-for-44 (.364).