Reilly Opelka, one of seven Americans ranked in the Top 40, gets very annoyed when asked repeatedly about the poor state of men’s tennis in the United States.

Although no American man has won a Grand Slam or been ranked No. 1 since Andy Roddick accomplished both in 2003, 21-year-old Sebastian Korda warned Thursday at the Miami Open Masters 1000: “We’re coming.”

Perhaps the most telltale sign that American tennis is on the upswing came last week when Taylor Fritz stunned Rafael Nadal, the all-time Grand Slam singles leader, in the final of the BNP Paribas Open, a prestigious Masters 1000 event at Indian Wells, Calif., to move up to a career-high 13. Fritz, the highest-ranked American, is scheduled to begin play Saturday.

Korda, who reached the quarterfinals here last year and has already reached the fourth round of two Slams, said Fritz’s win over one of the Big 3s — albeit a wounded Nadal (cracked rib) — inspired him. Korda said the close-knit group of Americans are pushing each other to get to the next level, just like Hall of Famers Jim Courier, Pete Sampras and Andre Agassi did in the ‘90s and early 2000s.

“Seeing Taylor doing his thing in [Davis Cup in Reno] and being part of it, cheering me on and then watching him do what he did at Indian Wells is inspiring,’’ said Korda, who coasted past Davidovich Fokina 6-1, 6-1 on Stadium Court.