By Steve Keating


NEW YORK (Reuters) - Romanian fifth seed Simona Halep advanced to the third round of the U.S. Open with a 6-3 6-4 win over Lucie Safarova on Thursday in the first full match played under a closed roof at Arthur Ashe Stadium.


The $150 million retractable roof was installed ahead of this year's tournament and guaranteed there would be at least some action on a muggy and overcast Day Four at the year's final grand slam.


"It was a little bit (of an adjustment)," Halep said about playing under the roof. "But I had the chance to warm up in the morning before the match.


"I don't want to say anything bad because it wasn't bad. Had a nice feeling.


"It was a great experience to be there. I didn't have to wait for the rain, so that's a good thing."

The roof, which has been a huge source of fascination for the Flushing Meadows crowds, was first used on Wednesday when it was put into action in the middle of Rafa Nadal's second-round victory over Andreas Seppi.

On a midweek morning session with the roof closed and a sparse crowd sprinkled through the massive stadium, Arthur Ashe had a vacuous, sterile atmosphere.

But more importantly, with rain delaying action on the other courts, play went ahead as scheduled on the main court where Halep needed 88 minutes to dismiss an error-prone Safarova, a two-time grand slam doubles champion, who committed a whopping 44 unforced errors.

Safarova, who last year reached a career-high number five in the world rankings, represented a tricky second round test for Halep, who wildly flailed her racquet during a first set temper tantrum at 3-3 before going on to break the Czech.

"I lost a little bit the rhythm," explained Halep. "But in the important moments I found the rhythm. I found the way that I have to hit.

"Always it's a good match against her. Gives me confidence that I can beat her."

Halep will play either Hungary's Timea Babos or Richel Hogenkamp of the Netherlands in the third round.

(Editing by Frank Pingue)