NEW YORK -- Almost three weeks after injuring his left groin, Yankees left-hander Nestor Cortes said he is still in recovery.

Cortes, who suffered the injury in Game 4 of the American League Championship Series against the Astros, started rehab last week. The 27-year-old has been working on Mondays, Wednesdays and Fridays. He believes he is close to recovery, but there’s still bruising in the area.

“I’m walking around great. I feel I can jog, but we are taking this very slow,” said Cortes, who attended the Lou Gehrig Legacy Gala at Chelsea Piers on Monday night. “Last time, we took it a little too fast. I reinjured it.”

In a game that sealed the Astros’ sweep of the Yankees, Cortes hurt the groin in the third inning. He left the game after allowing a three-run homer to Astros rookie phenom Jeremy Peña.

Cortes has been dealing with the injury since late August, when he was placed on the 15-day IL. The ailment was still bothering him when the postseason started, as the Yankees took on the Guardians in the AL Division Series. In Game 2, Cortes pitched with his groin in a heated wrap, tossing five innings of two-run ball in a no-decision as the Yankees lost.

Four days later, Cortes returned to the mound on three days’ rest, “put on my big-boy pants” and pitched five solid innings, helping the Yankees take Game 5 and advance to the ALCS.

The next time he pitched was Game 4 against Houston, when the injury made him leave the game early.

“The groin just went on me. I didn’t feel any pain. I didn’t feel any discomfort, but I knew my stuff wasn’t there,” Cortes said. “My velo had dropped. My stuff wasn’t there. … I tried to battle through it. I thought I was good enough to be competitive.”

Cortes had his best season to date in 2022, going 12-4 with a 2.44 ERA in 28 starts. He expects to be even better in 2023, and credits his great season to the strength coaches and the trainers on the Yankees’ staff.

“Being healthy most of the season helped me bring out the potential that I had,” Cortes said. “With the strength coaches, they found where I was lacking movement, where I was lacking flexibility. With that help, I was able to create more velocity. The velocity that spiked this year for me helped me be that successful. Hopefully from here [on out], I can keep on increasing velocity. I feel like I have more in me.”