- Rafael Nadal into fourth round of Masters 1000 Series at Indian Wells after a walkover
- Nadal will play Ernests Gulbis of Latvia for a quarterfinal berth in hard-court event
- Roger Federer also through to last 16, where he will play Stanislas Wawrinka
- Top women's seed Victoria Azarenka battles through after losing first set
He may be in need of match practice on hard courts, but Rafael Nadal had the good fortune of reaching the last 16 of the Masters Series 1000 tournament in Indian Wells without hitting a ball in anger Monday.
His third-round opponent Leonardo Mayer of Argentina withdrew before the start of their match on the Stadium Court, citing a back problem.
Nadal, who has slipped to No. 5 in the world rankings after a seven-month injury layoff, made his comeback last month in three clay court tournaments in South America, testing his troublesome knee.
He beat Mayer, his second career win over him, in the quarterfinals in Acapulco before going on to claim the title in confident style.
But the eyes of the tennis world were on Nadal as he returned to the more unforgiving hard court surface for the first time in 346 days with a second round match against Ryan Harrison of the United States Saturday.
The Spanish maestro came through that test 7-6 6-2 to advance to the third round of the tournament for the ninth time, bidding for his third title as the Californian event.
He will now get an extra day's rest before facing Ernests Gulbis of Latvia for a place in the quarterfinals Wednesday.
Gulbis, renowned for his fiery temperament, smashed his racket during the first set of his match against Andreas Seppi as he lost five straight games to concede it 7-5.
But he recovered with fine play in the second set before setting up victory as he broke his Italian opponent in the seventh game of the decider.
Gulbis served it out to win 5-7 6-3 6-4 to earn a crack at the 11-time grand slam champion.
If Nadal, looking to defend his French Open crown on his favorite clay surface later this year, can get past Gulbis, he is likely to face his first big test with a possible last eight clash against his great rival Roger Federer, the second seed.
Defending champion Federer, who said before the start of the tournament that he was "excited" by the return of Nadal to top flight action, thrashed Croatia's Ivan Dodig 6-3 6-1 to set up a fourth-round clash with his friend and fellow Swiss Stanislas Wawrinka.
Wawrinka, the 18th seed, won 6-4 7-5 against Australian veteran Lleyton Hewitt, who on Saturday beat last year's losing finalist John Isner.
Tenth seed Richard Gasquet set up a last-16 clash with world No. 6 Tomas Berdych, while fellow Frenchman Gilles Simon will take on big-serving South African Kevin Anderson.
In the women's draw, top seed Victoria Azarenka came from a set down to beat Belgian No. 28 Kirsten Flipkens 3-6 6-3 6-0.
The world No. 2 won 12 points in a row to extend her winning streak to 16 matches and set up a fourth-round clash with Poland's Urszula Radwanska.
"I'm really happy that I find the ability to turn around my matches no matter what the circumstances are on the court," said the Belorussian, who was criticized after taking a lengthy medical timeout before winning her Australian Open semifinal against Sloane Stephens in late January.
"To know when to take your opportunities is a learning experience. I'm glad I'm starting to master that."
Australian seventh seed Sam Stosur also went to three sets before beating China's Peng Shuai 6-3 3-6 6-2, earning a meeting with Germany's Mona Barthel -- who beat former world No. 1 Ana Ivanovic 6-1 3-6 6-0.
Caroline Wozniacki, another former No. 1, went through to the last 16 with a 6-2 6-1 win over Elena Vesnina and will next face another Russian in 10th seed Nadia Petrova.
German fourth seed Angelique Kerber also progressed, beating Belgium's No. 30 Yanina Wickmayer 6-1 7-6 (7-4) to set up a clash with 95th-ranked Spaniard Garbine Muguruza.