Serena Williams
Serena Williams (R- sitting) withdrew midway through her match against Garbine Muguruza. In this picture, Williams of the United States with medical staff after retiring from her match in at the start of the second set against Garbine Muguruza of Spain during their women's singles third round match on day seven of the BNP Paribas Open at the Indian Wells Tennis Garden in Indian Wells, California, March 10, 2019. Clive Brunskill/Getty Images

Serena Williams’ Indian Wells campaign came to an end on Sunday after the American withdrew midway through her match against Garbine Muguruza due to illness. It was the former world number one’s first tournament since her quarterfinal exit at the Australian Open.

The 23-time women’s singles Grand Slam champion, who beat former world number one Victoria Azarenka in her first match, was playing for the first time in five weeks. Williams made a good start as she raced to a 3-0 lead but then went on to lose six straight games to surrender the first set 6-3.

Williams revealed after her withdrawal that she had taken ill prior to her encounter and it got worse as the game wore on. The American called for the trainer during the changeover between sets and returned to court to face Muguruza, but her return did not last long as she withdrew immediately after losing the opening game of the second set to love.

"By the score, it might have looked like I started well, but I was not feeling at all well physically,'' Williams said in a statement distributed by tournament officials, as quoted by ESPN.

"Before the match, I did not feel great and then it just got worse with every second; extreme dizziness and extreme fatigue,'' Williams said. “I will focus on getting better and start preparing for Miami.''

Muguruza now progresses to the last 16 and will face number seven seed Kiki Bertens. She was sympathetic toward Williams after her win while wishing her a speedy recovery.

"It's really a weird feeling because I don't feel like I won the match point and well done, good match,'' Muguruza said. "It was just like, 'Man, we'll play next time.'''

The Spaniard also revealed that she had to make changes to her game after Williams raced to a 3-0 lead at the start of the match. Muguruza is the only player to have beaten both the Williams sisters – Serena and Venus – in tournament finals.

"I had to adapt a little bit my position in the court, the way I was hitting, and it took me a few games to kind of do it,'' Muguruza added. "Once I did it, I felt much more comfortable.''

Meanwhile, it was routine for Roger Federer and Rafael Nadal as they progressed without breaking too much sweat with straight set victories over Peter Gojowczyk and Jared Donaldson respectively. The Swiss ace won the first set 6-1 but had a more difficult second set, which ended 7-5 while Nadal surrendered just two games against this American opponent winning 6-1,6-1.