Serena Williams knew she had to do something — fast.

Down 3-1 to a qualifier on the first day of Wimbledon, the top-ranked player was not about to drop the opening set as she did four times during her run to the French Open title.

"She came out so fast, I was like, 'Oh my God, if I don't start I'm going to be down a set.' And I was tired of being down a set," Williams said.

So the five-time champion got to work, winning 11 of 13 games to beat 113th-ranked Margarita Gasparyan of Russia 6-4, 6-1 on Monday to extend her Grand Slam winning streak to 22 matches as she pursues a fourth straight major title.

Things were more straightforward for defending men's champion Novak Djokovic, who opened play on Centre Court and led all the way for a 6-4, 6-4, 6-4 win over Philipp Kohlschreiber of Germany.

"It's great to be back," said Djokovic, who beat Roger Federer in last year's final. "This is the cradle of our sport, Centre Court. It doesn't get any better than Wimbledon.

"I am privileged and honored to open this year's Wimbledon Centre Court as defending champion. It really is a special feeling."

Williams, who played the opening match on Court 1, is seeking to become the first player since Steffi Graf in 1988 to complete a calendar-year Grand Slam, a sweep of all four major titles in the same season.

Not only did Williams get off to another slow start Monday, she also got a warning for her language. In the sixth game, she received a code violation for an audible obscenity after sliding on the grass and falling during a point.

But Williams was able to impose herself on an opponent making her Wimbledon debut.

"I knew she would be a good player," Williams said. "I can't say I thought she'd be that good, to be honest."

Williams finished with as many errors — 19 — as winners, but she broke four times and lost serve only once.

"It feels good so far," she said. "Just to be back at Wimbledon, I have so many good memories here."

Kohlschreiber, the highest-ranked men's player outside the seedings at No. 33, had figured to pose a stiff test for Djokovic, who came to Wimbledon after a painful loss to Stan Warwinka in the French Open final and without having played a warm-up tournament on grass.

But the Serb was rarely troubled, seizing command with his all-court game, serving 12 aces and breaking five times.

"I had a very tough opponent who can be very tricky on all surfaces. Especially on the grass, he had nothing to do lose," Djokovic said. "I just managed to stay composed."

The 129th edition of Wimbledon opened in mostly sunny conditions with temperatures in the 20s Celsius (70s Fahrenheit). Forecasters are predicting a "heat wave" for London this week, with temperatures reaching 32 C (90 F) on Wednesday.

Other men's winners Monday included No. 9 Marin Cilic, No. 16 David Goffin, No. 17 John Isner and No. 26 Nick Kyrgios.

Women advancing to the second round included No. 7 Ana Ivanovic, No. 11 Karolina Plishkova and two-time Australian Open champion Victoria Azerenka.

The highest-seeded player eliminated was No. 9 Carla Suarez Navarro of Spain, who fell 6-2, 6-0 to Jelena Ostapenko of Latvia. Zarina Diyas of Kazakhstan upset No. 24 Flavia Pennetta of Italy 6-3, 2-6, 6-4.