Casper Ruud, of Norway, celebrates winning the first set against Karen Khachanov, of Russia, during the semifinals of the US Open tennis championships, Sept 9, 2022, in New York. (JOHN MINCHILLO / AP)

NEW YORK - Norwegian Casper Ruud harnessed his mighty forehand to reach his second Grand Slam final this year by beating Russian Karen Khachanov 7-6(5) 6-2 5-7 6-2 at the US Open, keeping alive his hopes of reaching the top of the world rankings.

The first Norwegian man to reach the final at Flushing Meadows won an extraordinary 55-shot rally to close the first-set tie break on his way to victory at Arthur Ashe Stadium.

The fifth seed next faces either home hope Frances Tiafoe or third seed Carlos Alcaraz of Spain in the final.

Ruud is known for his poise on clay but was equally effective on New York's hard courts, winning 14 straight points to build a 5-1 lead in a near-flawless second set

"This match is probably the biggest match for both of our careers," said Ruud, who was left humbled when he lost in straight sets to Rafa Nadal in June's Roland Garros final.

"You want to take care of the opportunities you have and I was able to do that today."

The 23-year-old Ruud is known for his poise on clay but was equally effective on New York's hard courts, winning 14 straight points to build a 5-1 lead in a near-flawless second set.

His form deteriorated in the third, where he racked up 11 unforced errors and handed Khachanov the break on set point.

However, Ruud bounced back to convert breaks on chances in the third and fifth game of the fourth set and clinched the contest with a forehand winner, one of 20 across the match.

READ MORE: Tiafoe makes history on tennis court named after pioneer Ashe 

Casper Ruud, of Norway (left) shakes hand with Karen Khachanov, of Russia, during the semifinals of the US Open tennis championships, Sept 9, 2022, in New York. (MATT ROURKE / AP)

It took ever ounce of his fitness - and a brave face - to survive the affair, as Ruud told reporters his legs were quaking from the marathon first-set point.

"I tried to not show Karen that I'm tired because I don't want him to think that, 'This is tiring for Casper'," he said.

"There is acting in sports. Tennis especially. It's such a mental and psychological game that any small detail can help you win the match."

Ruud would make the leap from world number seven to number one if he hoists the trophy on Sunday or if Tiafoe beats Alcaraz in their semifinal later on Friday, according to the ATP.

Khachanov, who rose to a terrific level to upset Australian Nick Kyrgios in a five-set quarterfinal thriller, said he was pleased to notch a few great wins in New York but was utterly exhausted from the grueling slate of competitors.

ALSO READ: Khachanov topples Kyrgios to reach US Open semis

"As the tournament (finishes), I feel really, really kind of destroyed in a way, really tired. All the energy went down. We're almost three weeks in New York, preparing the week before," he told reporters.

"I was thinking and dreaming obviously to lift the trophy."