New York - Steady rain prompted US Open officials to cancel 44 singles matches and postpone completion of 11 others under way when showers halted play Tuesday on the New York hardcourts.
Reigning French Open champion Jelena Ostapenko's first-round match against Spain's Lara Arruabarrena was under consideration to be moved under the roof at Arthur Ashe Stadium for completion.
The Latvian 12th seed led the Spaniard 6-2, 1-6, 3-1 when rain halted their match.
A US Open statement said weather forecasts predicted "continuous rain throughout the remainder of the day," prompting the wipeouts of outer court matches.
Still on the schedule were night matches sending 19-time Grand Slam champion Roger Federer of Switzerland against US teen Frances Tiafoe and US 15th seed Madison Keys against Belgium's Elise Mertens.
World number one Rafael Nadal's first-round match against Serbian Dusan Lajovic was in the first set on Ashe when the decision was made to end outer court play for the day.
The roof on Ashe was closed after the first set of the day's opening match -- world number one Karolina Pliskova's win over Magda Linette of Poland.
Results from day 2 of the US Open on Tuesday (x denotes seeding):
Karolina Pliskova (CZE x1) bt Magda Linette (POL) 6-2, 6-1
Barbora Strycova (CZE x23) bt Misaki Doi (JPN) 6-1, 6-3
Sorana Cirstea (ROM) bt Lesley Kerkhove (NED) 6-1, 6-3
Yanina Wickmayer (BEL) bt Lesya Tsurenko (UKR x28) 6-3, 6-1
Naomi Osaka (JPN) bt Angelique Kerber (GER x6) 6-3, 6-1