By Steve Keating
NEW YORK (Reuters) - Romanian second seed Simona Halep followed the same express path into the second round of the U.S. Open as Serena Williams, advancing 6-2 3-0 after New Zealand's Marina Erakovic retired with a knee injury on Tuesday.
The in-form Halep, who reached the finals at U.S. Open tune-up events in Toronto and Cincinnati, barely broke a sweat on a sunny Arthur Ashe Stadium court, needing a mere 47 minutes to see off the 99th ranked New Zealander.
Top seed Williams, bidding to complete a calendar sweep of the four grand slams, advanced on Monday in similar fashion as she was up 6-0 2-0 when Russia's Vitalia Diatchenko was forced to retire hurt.
While the top two women's seeds steered clear of trouble, upsets continued up and down the women's draw for a second consecutive day as sixth seed and French Open finalist Lucie Safarova fell 6-4 6-1 to Ukrainian Lesia Tsurenko.
With the loss, Safarova joins a number of first round casualties that already includes Serbian seventh seed Ana Ivanovic, eighth seeded Czech Karolina Pliskova and 10th-seed Carla Suarez Navarro of Spain.
"I wasn't surprised (by the upsets), it is normal," said 23-year-old Halep. "Everyone is fighting like crazy because it's the last grand slam (of the year). When you play the grand slam you have just to give everything you have.
"I had this year already two grand slams where I lost in first and the second round, so like I say always, everything can happen."
(Editing by Frank Pingue)