Jonathan Lewis, 20-year-old rookie, rapidly becoming key cog for New York City FC

Jonathan Lewis is used to expectations, but now New York City FC is getting to see what type of player he can become.

The 20-year-old rookie, who scored the late winner last weekend, has worked his way into a prime role in a matter of weeks. He’s become a complementary attacking piece and has found ways to score in both the starting 11 and coming off the bench.

“I think it’s just confidence,” Lewis said. “The coaches are believing in me, the whole staff is believing in me, so it’s being able to push on and keep pushing on.”

Lewis has started three games this season, most recently against the LA Galaxy on Aug. 12 when he also scored. He subbed on for five minutes against the New England Revolution on Saturday, enough time to score and prove that he can be a go-to option down the stretch.

But now comes the big test: The Blues’ second match against the rival Red Bulls (12-10-2, 38 points) this month.

“This can be a big part of our season,” Lewis said. “If we can get a win, we’re going to really create a gap between not only Chicago, but Red Bulls as well.”

Last time the two sides met, NYCFC (14-7-4, 46 points) was coming off a loss to Toronto FC. A win Friday at Red Bull Arena would give NYCFC a spotless August — four victories that would allow it to at least keep pace with Toronto for the Supporters’ Shield. There’s a four-point difference. But timing can matter less in a rivalry such as the Hudson River Derby.

“I think every derby, it’s easy to get up for a game like that,” said keeper Sean Johnson. “If you can’t get up for a derby game, there are other issues.”

This time around, the Red Bulls know they’ll have more scoring possibilities to contend with than David Villa, wherever Lewis comes from.

“Any way that I can play a part, whether it’s being supportive on the bench or being a start, I give my 100 percent,” Lewis said.