Syndergaard, a Toronto farmhand until he was part of a seven-play trade that brought fellow pitcher R.A. Dickey to the Jays in December 2012, will take the mound for the Mets in the opener of a two-game set in New York (7:10 p.m. ET).
Syndergaard, 22, hasn't been at his sharpest in his two starts this month and could have a mammoth challenge when he faces the team that drafted him Monday night.
The highly touted rookie right-hander will face a Toronto lineup that matched its longest string of victories with a 13-5 win in Boston on Sunday and had 16 hits to boost its average to .312 in its last 11 games.
The Blue Jays (34-30) have scored a whopping 8.0 runs per contest during their streak and counted 31 in their three games against the Red Sox this weekend.
"Honestly, I think everybody's coming here every day knowing we're going to win," infielder Ryan Goins said after driving in a career-high five runs Sunday. ''You put that with probably having the best one-through-six in the whole league and it makes it easier for seven, eight, nine."
The Blue Jays will try to keep rolling against Syndergaard (2-4, 4.15 earned-run average), the pitcher they took in the first round of the 2010 draft.
''I'm just going into it like it's another game,'' Syndergaard said. ''I don't really hold any grudges against them for that.''
The right-hander had a 1.82 ERA after his first four major league starts but has allowed 11 runs and 20 hits in 10 innings in his back-to-back losses this month. Syndergaard gave up four runs and 10 hits over six innings Tuesday while San Francisco's Chris Heston no-hit the Mets in a 5-0 defeat.
Syndergaard's counterpart on Monday is on virtually the opposite end of the experience scale, 36-year-old Mark Buehrle (7-4, 4.25). The veteran left-hander has also fared better in his recent outings, going 2-0 with a 2.25 ERA in his past three.
Buehrle nears mark
Buehrle yielded two runs in six innings while not getting a decision in a 4-3 win over Miami on Tuesday and couldn't register a third straight complete game. He's gone the distance in each of his last three road starts and will try to become the first Blue Jays pitcher with four consecutive complete games away from home since Dave Stieb in September 1982.
Curt Schilling is the last major league pitcher to do that with a five straight in 1999.
The Mets are the only team the 206-game winner has never beaten. He's 0-3 with a 4.39 ERA in four career matchups, last facing them in 2012.
New York (34-30) enters this game after hitting four homers and rallying from a five-run deficit for a 10-8 win against Atlanta on Sunday. The Mets' third victory in four contests kept them a half-game ahead of Washington in the National League East.
New York, 24-11 at home, will face the all-time winningest pitcher in interleague play with Buehrle going 30-10 in 51 starts. He's 5-2 with a 1.97 ERA in nine starts against NL teams since joining the Blue Jays in 2013 and is 3-1 with a 1.25 ERA in his last five.
Michael Cuddyer has faced Buehrle more than any other hitter, batting .318 in 110 at-bats with 11 doubles and three home runs.