The 28-year-old Wimbledon champion has only lost twice this year but found herself a break down in both sets before she recovered to seal her first victory since winning the Prague Open a month ago.

World No.2 Halep, who had skipped the US Open due to COVID-19 concerns and opted to stay in Europe and practice on the clay courts ahead of the French Open, looked sluggish at the Foro Italico with 14 winners offset by 15 unforced errors.

Halep had received a bye into the second round but was far from her best on serve and was broken five times in the match.

However, Paolini was also let down by seven double faults in the match while both players struggled to win games on serve, with six consecutive breaks marking the early stages of the second set.

Halep capitalised on Paolini's second serve, winning 15 of 17 points to take the opening set.

She switched gears late in the second to take the game away from the Italian, who was playing a top 10 player for only the second time in her career, as Halep finished the match after converting her eighth break point.

US Open finalist Victoria Azarenka overcame Venus Williams in the battle of former world No.1's

Azarenka, edged out in three sets by Naomi Osaka at Flushing Meadows on Saturday, beat 40-year-old Williams 7-6 (11-9) 6-2 in the first round.

"I felt that this was a great match for me to figure it out, the first match on clay," Azarenka said.

"Venus played a really good match, it was good to see her also adapting to clay, changing and trying different shots. So, I'm pretty happy."

Azarenka will meet American third seed Sofia Kenin in round two.

Australian Associated Press