NEW YORK -- Justin Verlander is inching closer to a return.

The Mets pitcher -- who started the season on the injured list with a muscle strain -- threw off of flat ground Tuesday and had a "really good day," according to manager Buck Showalter.

The next step will be for Verlander to head down to the team's facility in Port St. Lucie, Florida, where he will throw a side session and make a rehab assignment while the team makes a West Coast swing to play the Athletics, Dodgers and Giants.

"Very close to putting his foot on the pedal a little bit," Showalter said Wednesday. "The people that work with him were very encouraged."

Verlander hoped he would not have to make a rehab assignment, but the team erred on the side of caution.

"He's champing at the bit, but we want to make sure we resolve everything in there before we turn it loose," Showalter said.

The injury is a low-grade teres major strain. The muscle is located on the underside of the upper arm between the elbow and shoulder.

The Mets and Verlander agreed to a two-year, $86.6 million contract ahead of this season after the 40-year-old righty put together one of the best seasons in his career in 2022.

Upon returning from Tommy John surgery, Verlander posted a 1.75 ERA, 0.83 WHIP and 5.9 bWAR in 28 starts with a 18-4 record.