Serena Williams opened her bid for a 24th Grand Slam title on Tuesday with a straight-sets victory on Centre Court at Wimbledon.
The seven-time champion at the All England Club beat Giulia Gatto-Monticone of Italy 6-2, 7-5.
Williams, who lost in the Wimbledon final last year, is short on matches and training time this season, factors she cited after her third-round exit at the French Open, her most recent tournament.
Williams has been dealing with an injured left knee. She said Saturday she has been "feeling better," and her coach, Patrick Mouratoglou, said the 37-year-old American "doesn't have pain anymore."
If her knee is fine, that not only helps her cover the court, of course, but also allows her to get some extra oomph on her serve, which when at its best is the best in the game.
"I can actually use my legs now. It's been a while,'' said Williams, who pounded serves at up to 122 mph on Tuesday. "Mentally, if you're serving without legs, you're paranoid [about] hurting your shoulder, so you take a little pace off. ... Now that I can actually use my legs, it just all feels better."
The 31-year-old Gatto-Monticone was making her debut in Wimbledon's main draw.
"Incredibly happy to play her,'' Gatto-Monticone said afterward. "Serena is Serena.''
To get to match point, Williams smacked a swinging forehand volley winner, then pumped both arms, leaned forward and screamed.
Asked about that vigorous celebration, Williams explained that she feels as if "every match counts like several matches,'' because she is trying to make up for lost time.
"That was just something that I was really excited about,'' she said, before referring to herself in the third person: "It's Serena; I always get excited.''
Maria Sharapova retired from her first-round match with a left wrist injury while trailing 5-0 in the third set.
The 2004 Wimbledon champion served for the match while leading 5-3 in the second set but lost to Pauline Parmentier of France 4-6, 7-6 (4), 5-0.
Sharapova, who was unseeded at the All England Club for the first time since her debut in 2003, called for a medical timeout after the second set and a trainer put some tape on her wrist. She called for the trainer a second time in the third set, and she stopped just after Parmentier served for the 5-0 lead.
This year's Wimbledon was only Sharapova's second tournament since January following shoulder surgery. She lost in the second round in Mallorca last month.
"I've had a history of a tendon in my left forearm flaring up," Sharapova said Tuesday. "It happened today in the second set."
Two-time Wimbledon champion Petra Kvitova won her opening match, only days after deciding she was healthy enough to even take part in the tournament.
Kvitova, who won the grass-court Grand Slam in 2011 and 2014, beat Ons Jabeur of Tunisia 6-4, 6-2 on No. 3 Court.
The sixth-seeded Czech reached the Australian Open final and won tournaments in Sydney and Stuttgart this year, but she missed the French Open with a left forearm injury.
The American was one of four top-10 seeded women to lose in the first round last year, and she also went out in her opening match in 2017. Bacsinszky reached the quarterfinals in 2015, but she now has lost all three of her career meetings with Stephens.
Barty overtook Naomi Osaka last week for the top ranking and lived up to the status on No. 1 Court, breaking her Chinese opponent twice in each set.
"It feels incredible,'' Barty said about playing at Wimbledon as the top-ranked woman. "It's a little bit of a bizarre feeling, to be honest. But I just try and go about my business the exact same way.
"This hallowed turf that we do get to play on is sacred, it's beautiful. And you have to enjoy every minute."
Former women's champion Garbine Muguruza is heading home early again.
Muguruza lost to Brazilian qualifier Beatriz Haddad Maia 6-4, 6-4 in the opening round, making for a second straight early exit for the Spaniard since winning the title in 2017. She lost in the second round last year.
The Associated Press contributed to this report.