All eyes on defending champion Carlos Alcaraz as he makes return at US Open

Alcaraz, sidelined since April with a right wrist injury, is trying to bookend his season with Grand Slam titles after his Australian Open triumph in January made him the youngest man to complete a career Grand Slam.

He's part of a jam-packed second day schedule that also sees two-time women's defending champion Aryna Sabalenka, six-time Grand Slam winner Iga Swiatek, four-time major champion Naomi Osaka in action along with Wimbledon champion Linda Noskova.

AFP Sport looks at three matches to watch on Day 2 of the US Open:

Roman Safiullin v Carlos Alcaraz (1-1)

Alcaraz faces a potentially tough first test against hard-hitting Safiullin, who beat Andrey Rublev and Joao Fonseca on the way to the Wimbledon fourth round, where he fell to Novak Djokovic in four sets.

The 29-year-old Russian has the ability to push Alcaraz from the baseline. He upset then second-ranked Alcaraz at the ATP Paris Masters in 2023, a defeat Alcaraz avenged the next year at the Paris Olympics.

Alcaraz says demanding practice sessions have built his confidence in his wrist and he's ready to "go 100 percent".

Aryna Sabalenka v Camila Osorio (2-0)

Sabalenka has been in free-fall since winning back-to-back hard court WTA titles at Indian Wells and Miami in March, so much so that the Belarusian could lose her world number one ranking even if she becomes just the third woman -- after Chris Evert and Serena Williams -- to win three US Open titles in a row.

Her two wins over 59th-ranked Osorio came on the grass of Wimbledon in 2021 and on clay at Madrid in 2023.

Sabalenka, who lifted the title in Brisbane before reaching the Australian Open final in January, insists her mid-season swoon -- featuring a quarter-final exit at Roland Garros and a fourth-round loss at Wimbledon -- hasn't dimmed her confidence.

"Throw tough challenges at me, I will come back stronger," she says.

Naomi Osaka v Anastasia Zakharova (First meeting)

Japan's Osaka counts two US Open titles, in 2018 and 2020, among her four Grand Slam victories.

"I think I've proven myself here, so I can kind of bank on that and use that to have confidence," said Osaka, who reached the semi-finals of the Washington hard court tournament before a run to the quarter-finals in Toronto this month.

It's been five years since Osaka won her most recent Grand Slam title in Australia. She has spoken candidly about mental health issues and in addition to taking time away to focus on that she took 15 months off to focus on motherhood before returning in 2023.

Her best-ever quarter-final run at Wimbledon this year included an upset of Sabalenka, and on the more comfortable hard courts of Flushing Meadows she'll be seeking a quick start against 101st-ranked Zakharova.