Manager Luis Rojas revealed as much when talking to reporters Tuesday, calling it a "small" fracture that has not led to any "major concern." Rojas said Lugo will have padding on his spikes since he lands on the left foot when he does pitch.
Lugo, who was part of the Mets' starting rotation in 2017, was a key part of the team's bullpen last year.
He appeared in a career-high 61 games and finished with an impressive 2.70 ERA, 0.90 WHIP and 104 strikeouts in 80 innings. It marked the third time in his four years in the major leagues he finished with an ERA under 3.00 and WHIP under 1.10.
New York's bullpen features a number of notable names and could be one of its strengths if everyone remains largely healthy.
Lugo is part of a group that could also include Edwin Diaz, Dellin Betances, Jeurys Familia, Robert Gsellman, Brad Brach and Justin Wilson.
Having a setback like this in spring training is less than ideal, but the fact that Rojas said there isn't much concern and Lugo is already testing it by walking around suggests the right-hander should be back well before Opening Day.