A year ago, New York Mets left-hander David Peterson was in the midst of a first-half breakout that helped him earn a spot on the National League All-Star team.

Now, Peterson has been scratched from his latest start as skidding New York looks for a spark.

The Mets will aim to end their longest losing streak in more than 20 years on Sunday afternoon when they visit the Chicago Cubs in the finale of a three-game series.

The Mets announced late Saturday that right-hander Tobias Myers (0-1, 3.46 ERA) will start in place of Peterson, who reportedly is not injured. Right-hander Javier Assad (1-1, 8.10 ERA) will start for Chicago.

The Cubs handed the Mets their 10th straight loss Saturday afternoon, 4-2, after pinch-hitter Carson Kelly belted a go-ahead, three-run homer in the sixth inning.

The skid is the longest for the Mets since they dropped 11 in a row from Aug. 28-Sept. 8, 2004. New York has been outscored 60-18 during the current streak and hasn’t led at the end of an inning since the first frame of an 11-6 loss to the Athletics on April 11 — a span of 62 innings.

The Mets, who have six new starters in their everyday lineup after parting ways with Pete Alonso, Jeff McNeil and Brandon Nimmo over the winter, are 7-14 overall. It’s the worst 21-game start for the franchise since the 1983 team opened 6-15 on its way to finishing 68-94.

“Nobody’s going to feel sorry for us; you’ve got to keep going,” Mets manager Carlos Mendoza said. “We haven’t been playing good baseball. That’s the bottom line.”

Peterson has been struggling since his first All-Star Game appearance. The southpaw is 0-3 with a 6.41 ERA in four starts this year and 3-5 with a 6.35 ERA in his last 16 starts dating to July 20.

Myers, who hasn’t started since Aug. 9, has pitched at least 1 1/3 innings in each of his six games this year. He has thrown at least 30 pitches four times — including in his most recent appearance Wednesday, when he allowed one run over two innings in the Mets’ 8-2 loss to the Los Angeles Dodgers.

Kelly’s second career pinch-hit homer continued an impressive week for the Cubs, who have won four straight games.

Chicago’s streak of consecutive games with least 10 runs scored was snapped at three Saturday, but the Cubs have scored 51 runs in the last six games after scoring 59 in the first 14 games of the season.

The Cubs also have pitched well during their winning streak despite the loss of closer Daniel Palencia, who was placed on the 15-day injured list Friday due to a strained left oblique.

Jameson Taillon gave up one run over six innings Saturday in the third straight quality start for the Cubs, whose relievers have a 3.17 ERA during the winning streak. The surge began Tuesday, when Colin Rea allowed three runs over six innings against Philadelphia as a bulk reliever.

Caleb Thielbar earned the first save of the streak Saturday when he struck out two in a perfect ninth. It was just the sixth career save for the 39-year-old Thielbar, who has made 422 big league appearances dating to 2013.

“This group, we’re always prepared,” Kelly said. “We’re always looking for that opportunity. Just as a group, we’re pulling for each other at all moments.”

Assad took the loss in his most recent start last Monday, when he gave up nine runs over 4 1/3 innings as the Cubs fell to the Phillies 13-7.

Myers is 0-2 with a 4.67 ERA in five career games (three starts) against the Cubs. Assad is 1-1 with a 3.45 ERA in four games (three starts) vs. the Mets.

–Field Level Media