LOS ANGELES -- Nowadays, beating the Dodgers demands a certain degree of execution, an ability to perform critical tasks, big and small. Not too long ago, a lesser effort would have been enough. But now, this standard is unyielding.

The Mets spent much of Monday night on the brink of meeting those demands, but in the critical moments of a 4-2 loss, there was no hiding their imperfections.

Righthander Jenrry Mejia allowed three runs -- two earned -- in six innings. But the Mets were undone thanks to shaky defense in the sixth, which transformed a two-run lead into a one-run deficit.

Second baseman Daniel Murphy got caught in between on Carl Crawford's grounder, then let Mark Ellis' soft liner glance off the edge of his glove. The hits set up the Dodgers' key three-run inning.

"Those were two plays I thought I could make, personally," said Murphy, who absorbed another dose of frustration in the seventh, when he watched Dodgers star Yasiel Puig take away what could have been a game-changing hit.

Instead, the Dodgers quickly made a comeback more difficult when Nick Punto homered off Carlos Torres, padding their lead to two runs.

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The Mets had their chances. They settled for scoring only two runs in the second, when they had the opportunity to rack up more damage against Dodgers righthander Ricky Nolasco, but watched as their rally stalled partly because Mejia couldn't put down a bunt.

In the seventh, the Mets left the bases loaded. In the eighth, their two-out rally fizzled. With that, the once-struggling Dodgers pressed on for their 38th victory in their last 46 games. They are 21-3 since the All-Star break.

Mejia (1-2) took the loss despite a night in which he recorded his third quality start.

"I've been very impressed," Mets manager Terry Collins said.

The Mets have turned their season around by tightening a defense that had once been porous. That trend seemed to continue into Monday night when rookie third baseman Wilmer Flores made a sparking diving stop in the fourth to rob Ellis.

The play was even more impressive because Flores twisted his right ankle when his foot slipped off second base in the first inning. Between innings, he had his ankle taped. But in the clubhouse afterward, the 22-year-old hobbled after a long stay in the trainer's room.

"Not too bad, just sore, that's it," said Flores, who insisted he'd be ready to play Tuesday night.

The Mets took a 2-0 lead only to watch it all come undone in the sixth. After Crawford and Ellis reached, Adrian Gonzalez lined a single just over the glove of shortstop Omar Quintanilla. Crawford scored easily ahead of Ellis, who came home only after centerfielder Juan Lagares bounced a throw past Flores.

The error allowed Gonzalez to reach third, bringing up Puig, whose sacrifice fly gave the Dodgers a 3-2 lead. Puig struck again in the seventh, this time using his glove to squash a Mets rally, running down Murphy's deep drive. It was the final insult in an inning that began to go sour when with the bases loaded, Lagares took a called strike three on a pitch that appeared outside of the strike zone.

Said Lagares: "There's no way that pitch is a strike."