Igarashi, who has emerged as the Mets' top eighth-inning option, left after recording the second out. He had felt something in his hamstring while attempting to field a bunt by Koyie Hill, the first batter of the inning.
Igarashi flubbed the bunt for an error but pitched to two more batters, retiring both. He was unable to continue and was replaced by Fernando Nieve, who got the final out of the inning. It was Nieve's 10th appearance in the first 14 games.
Igarashi will have an MRI Wednesday at the Hospital for Special Surgery.
"I felt a little stretch on my hamstring," he said through an interpreter. "I felt that nothing really popped up and I was able to keep throwing. As I continued pitching, I felt numbness in the region."
The Mets could recall righthander Tobi Stoner, who made one appearance Sunday before being sent down when Ike Davis came up. Among the other candidates from Triple-A Buffalo, Bobby Parnell has a 6.35 ERA and has walked seven in 5 2/3 innings and veteran Kiko Calero has a 6.14 ERA in four outings.
Manager Jerry Manuel took pains to say, no, that's not accurate. He changed things around to get better matchups in the season's first two series, but Manuel also insisted Niese had earned the promotion.
Niese had his best outing of the season on Monday when he threw 5 2/3 innings against the Cubs and was charged with one unearned run. He allowed eight hits and three walks, but showed a knack for getting out of trouble. Seven strikeouts helped.
"I thought he was very good," Manuel said. "We felt out of spring that he was actually a guy that was throwing the best probably out of the five. We thought he was throwing real well, so there wasn't much hesitation in bumping him up."
Niese, who got a no-decision in the Mets' 6-1 win, is 0-1 with a 4.32 ERA in three starts. He has been working on a cutter; it had slider-like action on Monday and was a strikeout pitch.
"We felt that what we saw last year . . . we were seeing some of the maturation process," Manuel said. "That seemed to have continued in spring training. The evolution of his repertoire. He seems to be enjoying the fact that he can do different things with the baseball and compete at the major-league level. That's a good sign. That's a very good sign."
Overall, Mets starters had a 4.46 ERA before last night. That's 10th in the National League.
Franchise to appear
The VIP entrances on the first- and third-base sides of the stadium were renamed before the season. They had been called the "First Base" and "Third Base" VIP entrances before the ballpark was remade to better honor the team's history.
Jason Bay was 0-for-2 with a walk and two strikeouts. The Mets' $66-million leftfielder has fanned 21 times in 51 at-bats . . . Mets starters have an 0.95 ERA in the last six games . . . Mike Pelfrey is 7-1 with a 2.81 ERA in his last eight decisions in April dating to 2008.