It was Sharapova's first Grand Slam match since a quarter-finals loss to Serena Williams in last year's Australian Open, when she tested positive for the newly banned heart drug meldonium. Furthermore, Sharapova aims to keep her record blameless over Halep which now stands at 6-0.
'I'm sad, of course, losing this match, ' said the second seed. The ban was initially supposed to last two years, but got reduced to 15 months in October 2016.
Meanwhile, Sharapova praised the grit of Halep, saying that "she is not going anywhere".
Sharapova will play Hungary's Timea Babos in the next round. Sharapova will be a longshot to win her sixth major championship and second US Open. She received a wild card into the U.S Open and will face Halep in Monday's night session. Jelena Ostapenko, who won this year's French Open, is seeded 12. She is now 18-0 in evening matches on Arthur Ashe Stadium at the U.S. Open after beating world No. 2 Halep of Romania 6-4, 4-6, 6-3 in an nearly three-hour battle.
Having only converted 17 out of a possible 22 break points along with 64 unforced errors, the 30-year-old did, however, slam 60 winners as she eventually won in a contest that lasted two hours and 44 minutes as the crowd stood up and applauded.
Sharapova now owns a 7-0 career record against Halep. I'm sure it helps with my motivation and confidence but after that you have to go out there and play.
In the second set alone, Halep staved off five break points before clinching the 10th game and forcing a third set.
Sharapova added: "I was looking forward to it".
Muguruza, meantime, has been installed by bookmakers as the favorite to win back-to-back Grand Slam titles after her Wimbledon triumph earlier this summer, but she isn't ready to acknowledge that.
Some observers accused the five-time grand slam champion of an act of deception before the third set to halt Halep's momentum.
"It's all about the balance, finding a nice spirit of competition and also enjoying a little bit of the city but not getting overwhelmed by it", Muguruza told reporters.
Even though Sharapova's sometimes sloppy play carried over to the final set, her mistakes were fewer and farther between. She then cited the same problem as reason for withdrawing from Toronto and Cincinnati as she sought reassurance from specialists that she would be able to play here in NY.
It was the type of all-or-nothing assault that has served her well since she first burst on the scene with a 2004 Wimbledon title.
Her opening round win revealed a side of Maria Sharapova rarely seen by the general public.