INDIAN WELLS - World number ones Novak Djokovic and Serena Williams had to dig deep at Indian Wells on Sunday to fend off a pair of unheralded but spirited opponents. Williams stepped up her bid for her first Indian Wells title in 15 years with a straight-set 7-6 (7/2), 6-0 victory over 56th-ranked Yulia Putintseva. Djokovic dropped the first set before coming from behind to book his third-round spot in the ATP and WTA hardcourt tournament with a 2-6, 6-1, 6-2 victory over 149th-ranked qualifier Bjorn Fratangelo. In the evening session, reigning champion Simona Halep steamrolled Ekaterina Makarova 6-2, 6-4 to get her title defence off to a flying start.

The two-time Indian Wells champion Williams had a difficult time with Putintseva in the opening set but then steamrolled through the second to wrap up the win in one hour, 15 minutes. "The first set was a little tricky, then I had to find my inner tiger... and roar," said Williams, who booked a fourth-round clash with Kateryna Bondarenko.

Williams has a chance to become the first three-time winner in women's singles at Indian Wells, a feat she failed to achieve last year when she was forced to withdraw from her semi-final with a knee injury. Williams, who won the event in 1999 and 2001, returned to the tournament last year, ending a 14-year boycott which began after she beat Kim Clijsters in the 2001 final. That year spectators at Indian Wells booed Williams during the final and jeered her sister, Venus, and father Richard Williams when the pair arrived to watch the match. Richard Williams alleges that racists comments were directed at them.

As the top seed and a 21 Grand Slam champion, Williams is the clear favourite this week. And her quest was boosted with the early elimination of two of the top five seeds in the women's draw, Angelique Kerber and Garbine Muguruza. Although Williams got off to a poor start Sunday, she closed out the contest in style with an ace on match point. "I was just trying to find my rhythm out there, trying my best to not get off to a slow start," she said. "Just trying to fight."

The defending two-time men's champ Djokovic has now won 12 consecutive matches in Indian Wells and is seeking to become the first player in tournament history to claim five titles. Djokovic won 78 percent of his first serve points, made three double faults and had his serve broken three times including twice in the first three games. He returned the favour in the deciding third set by breaking Fratangelo in games one, five and seven. "All in all, it was just not a great performance," Djokovic said. "But you have to deal with it, accept it. A win is a win. Hopefully the next one will be better."

After the victory in difficult, windy conditions, Djokovic next faces German Philipp Kohlschreiber who swept past Denis Kudla 6-0, 6-1. "Today is one of those days where you don't feel the ball well," Djokovic said. "You know, swirly conditions." Japanese star Kei Nishikori eased into the third round with a 6-3, 6-3 win over Kazakhstan's Mikhail Kukushkin. The 26-year-old Nishikori, seeded fifth in his eighth appearance in Indian Wells, has never made it past the fourth round in the California desert. "It is not easy playing the first match of any tournament," Nishikori said. "But I felt comfortable today. So I hope I can go further than the last couple of years."

Jo-Wilfried Tsonga defeated French compatriot Vincent Millot 7-5, 6-1; Dominic Thiem beat Jozef Kovalik 7-6 (7/4), 7-6 (7/3); and Sam Querrey stopped Thiemo de Bakker 7-6 (7/5), 6-4. Elsewhere in women's action, world number three Agnieszka Radwanska breezed past Romania's Monica Niculescu 6-2, 6-1 to reach the fourth round. Last year's runner-up Jelena Jankovic crushed CoCo Vandeweghe 6-0, 6-1 and Czech Petra Kvitova defeated Swede Johanna Larsson 6-3, 4-6, 7-5.