The New York Mets' status as NL East leaders can be traced to their outright dominance of the Philadelphia Phillies.
The Mets go for a franchise-record 11-game winning streak against the Phillies on Tuesday night.
New York (73-58) has built a 6 1/2-game lead on second-place Washington and facing major league-worst Philadelphia (52-80) is aiding its hunt for its first division title in nine years.
The Mets have won 23 of the past 27 matchups, including 13 of 14 this year. Their 10-game winning streak against the Phillies matches their longest in the series set from 1971-72.
A victory Tuesday would make this streak the second-longest in team history against an opponent, tying a run versus San Diego in 1969 and their current one against Colorado.
New York extended its home winning streak against Philadelphia to eight after opening this three-game series with a 3-1 victory Monday.
The Phillies are tired of losing to their fierce rival.
"We're going to take it to them the next two days," interim manager Pete Mackanin said. "We've got to beat them."
That would mean beating Jonathon Niese (8-9, 3.95 ERA) for the first time since April 28, 2013.
The left-hander is 5-0 with a 2.24 ERA while each of his last eight starts against the Phillies have ended in Mets wins. He's 3-1 with a 1.50 ERA in his past five home matchups.
Niese wasn't that sharp at Philadelphia on Thursday, giving up five runs in the third before leaving after the sixth of a 9-5 win in 13. He issued a season-high five walks and hit a batter five days after allowing seven runs and 11 hits in 5 1-3 innings of a 14-9 win at Colorado.
He should feel more comfortable at Citi Field, where he's 1-0 with a 2.84 ERA over his last three starts.
Curtis Granderson is hitting .353 with three homers, eight RBIs and 13 runs in his past 12 games. That includes going 6 for 17 in four against the Phillies after hitting a two-run blast Monday.
Michael Conforto is also hot, going 2 for 2 with a solo shot Monday to give him a .458 average in his last nine contests. The rookie left fielder hit .224 over his first 20 games.
He's 6 for 13 over the last three meetings with Philadelphia, driving in one run in each.
"I feel a little bit more comfortable," Conforto told MLB's official website. "I just had to go back to working hard, getting into the cage and working on some things, take a step back and ... go back to the drawing board and figure it out. But I do feel comfortable."
The Phillies, losers of six of eight, hand the ball to Aaron Harang (5-14, 4.79), who is tied with Milwaukee's Matt Garza for the most losses in the majors.
The right-hander is 0-3 with an 8.04 ERA in his past five starts, wasting a five-run lead Thursday. He surrendered five runs and three homers in six innings.
Harang is 0-2 with a 3.79 ERA in three starts against New York this year, and this will be the third straight with Niese also getting the call.
Granderson is 3 for 9 against Harang this season after going 1 for 12 to start his career.