Defending champion Carlos Alcaraz returns to action at Flushing Meadows following a four-month injury layoff during the week as he looks to the quaerter-final on Sunday night. | AFP

Defending champion Carlos Alcaraz will be under the microscope again on Sunday taking on 20th-seeded American Tommy Paul for a place in the US Open quarter-finals.

The Spaniard, playing his first tournament since a four-month absence with a wrist injury, acknowledges he has yet to play his best but says he's "getting there" with both the sharpness of his shots and his on-court decision making.

He headlines a day that also features women's two-time defending champion Aryna Sabalenka and third-ranked American Jessica Pegula -- just one of the players with a chance to supplant Sabalenka atop the world rankings in New York.

Surprise Wimbledon champion Linda Noskova will try to continue her progress toward another Grand Slam against dangerous Ukrainian Marta Kostyuk while US hope Frances Tiafoe faces the always tricky former champion Daniil Medvedev.