Novak Djokovic to vie for fourth US Open title after downing home favourite Ben Shelton

Djokovic, 36, halted big-serving 20-year-old Shelton's breakthrough run with a 6-3 6-2 7-6 (4) victory.

The gulf in big-occasion experience was apparent from the start, with Djokovic playing in his 100th US Open match and Shelton his seventh.

Shelton was the youngest American man to reach the semi-finals since Michael Chang in 1992, Djokovic the oldest since Jimmy Connors a year earlier.

The Serbian was playing in his 47th grand-slam semi, and Shelton his first.

Now Djokovic is one win away from a 24th major title and becoming the oldest winner in the Open era, surpassing Ken Rosewall who was 35 when he won the title in 1970.

"Look, these are the kind of matches and occasions that I still thrive on, that inspire me to wake up every day and work hard," Djokovic said.

"Grand slams are the most important, the ones that mean the most to me. Playing an American player is never easy and I had to hold my nerve. It was anybody's game at the end of the third set. I'm really pleased with this win today."

A poor service game saw Shelton gift Djokovic a break in the first set with three unforced errors including an ill-advised drop shot.

The youngster saved four set points on his own serve and had a break-back point in the next but was unable to take it as Djokovic got the first set on the board in 34 minutes.

A double-fault gave Djokovic another break in the second as Shelton's unforced errors really began to pile up; by the end of the second set he had made 27 to Djokovic's nine.

Shelton gave the New York crowd something to cheer in the third when he twice retrieved breaks and had a set point on the Djokovic serve.

It was quickly snuffed out, though, and Djokovic prevailed in the tie-break to book a 36th grand slam final - which is incredibly half of the majors he has competed in.

Djokovic mimicked Shelton's ˜dialled in' phone call celebration as he approached the net.

"I didn't see it until after the match," said Shelton. "You know, I don't like when I'm on social media and I see people telling me how I can celebrate or can't celebrate. I think if you win the match, you deserve to do whatever you want.

"As a kid growing up, I always learned that imitation is the sincerest form of flattery, so that's all I have to say about that."

READ MORE: Naomi Osaka hints at emulating Serena and Venus Williams to play until her forties