A day after the Mets officially announced signing the 25-year-old southpaw to a five-year, $25.5 million contract extension with two team options, Niese makes his season debut against visiting Atlanta.
"Jon Niese is going to be a good pitcher for a long time," Mets manager Terry Collins said. "I think it's a great move by us to lock him up."
The Mets are looking to sweep the Braves out of New York after taking the first two games of the season-opening series.
The Braves will counter with a southpaw of their own, Mike Minor, who posted a 3.51 ERA in his final 10 starts of the 2011 campaign and also threw well in Spring Training.
He did run into trouble -- on March 23 against the Mets -- after not allowing a run in 14 exhibition innings leading into that game, but he was pleased with how he managed to work out of a jam in the 9-4 win.
"It was just one of those days where I was glad I had it, because it's just Spring Training," Minor said. "I feel like I need those kinds of games where you don't feel like you have everything and you need to get through it. It was good practice to get out there and struggle like that."
Meanwhile, Niese, the Mets' seventh-round pick in the 2005 First-Year Player Draft, is entering his third full season with the club. He's coming off a season in which he went 11-11 with a 4.40 ERA, recording 138 strikeouts over 157 1/3 innings before a right intercostal strain in August cut short his campaign.
He was 1-1 with a 5.73 ERA in six Spring Training games (five starts).
The Mets have begun the season 2-0 for the first time since 2009, when the club won its first two games in Cincinnati. New York won its first four in 2007.
Braves: A familiar face in a new spot
Veteran right-hander Livan Hernandez made his Braves debut on Saturday, coming out of the bullpen with two men on and one out in the fifth inning of a tied ballgame. He allowed three hits and struck out one in 1 2/3 innings of scoreless work, but he did allow an inherited runner to score.
Hernandez, 37, is starting his 17th season in the big leagues after spending the last three with the Nationals. It was his first Major League relief appearance since his debut in 1996.
Mets: Calling for reinforcements
The Mets recalled outfielder Kirk Nieuwenhuis from Triple-A Buffalo before Saturday's game when the club placed outfielder Andres Torres on the 15-day disabled list. Nieuwenhuis hit eighth and played center field, going 2-for-4 in his Major League debut.
After tossing four shutout innings on Opening Day and three more on Saturday, the Mets' bullpen has a spotless ERA. Last season, the Mets' bullpen finished 28th in the Majors with a 4.33 ERA and blew 24 games, the seventh most in baseball.
Dating back to the last game of 2011, Mets catcher Josh Thole has multihit games in three consecutive contests.
After shutting out the Reds in last year's season finale and the Braves on Opening Day, the Mets' pitching staff extended its scoreless-innings streak to 22 2/3 frames before a Martin Prado home run in the fifth inning Saturday.