US Open champion Aryna Sabalenka credited Jessica Pegula after prevailing 7-5 7-5 in a thrilling Flushing Meadows final.

A topsy-turvy encounter saw Sabalenka cruise into a 3-0 lead in the second set, only for Pegula to reel off five straight games.

Yet Sabalenka regained her composure to propel herself back into the lead, with a long Pegula return from a ferocious volley sealing the Belarusian's maiden success in New York.

"Oh my God, I'm speechless right now," Sabalenka, last year's runner-up, said in the on-court presentation.

"So many times I thought I was so close to winning the US Open title, it's always been a dream of mine and finally I got this beautiful trophy. It means a lot, it was a really difficult couple of weeks."

Sabalenka then turned to Pegula, who became the oldest American player to compete in her first grand slam final.

"Jessica, I know how tough it was in the finals but you are showing some amazing tennis and I'm more than sure that you are going to get one [title], I mean not one, maybe more but let's start with one grand slam," said the Belarusian, who has now won three major titles.

"Congratulations on a great summer and you're an amazing player and in that second set honestly I was really praying for getting this win and not giving you one set.

"It means a lot, I'm literally speechless right now."

Pegula, who lost to Sabalenka at the Cincinnati Open last month, is the first player aged 30+ to reach their first grand slam singles final since Flavia Pennetta (33y 197d) and Roberta Vinci (32y 204d), at the 2015 US Open.