MIAMI: Novak Djokovic and Maria Sharapova both survived unscathed but the Sony Open lost two other grand slam champions on Friday when Victoria Azarenka and Juan Martin Del Potro exited the Miami tournament.
Azarenka withdrew from her opening match because of an ankle injury she suffered playing at Indian Wells last week.
"I'm very disappointed ... But I have to take my health into consideration," said Azarenka, who won the Australian Open in January but has struggled with injuries since.
"I tried everything I could but couldn't make it. It's an unfortunate part of our job."
Azarenka's withdrawal proved an unexpected bonus for American teenager Lauren Davis, who failed to qualify for the tournament.
She was given a 'lucky loser' pass into the event when Azarenka pulled out then saved three match points in defeating Madison Keys 6-1 5-7 7-6.
"I just hoped and I wished and I prayed that I would get in," said Davis. "I was just so happy. I didn't care if I won or lost. I just was so grateful for the opportunity to play."
Former US Open champion Del Potro suffered a surprise 7-6 6-1 loss to Germany's Tobias Kamke.
The towering Argentine had two set points in the opening set but lost his way just a week after making the men's final at Indian Wells.
"He didn't play obviously his best tennis," said Kamke. "But still I think I did a good job and pretty satisfied with that."
There were no other major casualties among the top seeds, with Djokovic and Sharapova both winning in straight sets.
Sharapova romped to a 6-2 6-0 win over Canada's Eugenie Bouchard while Djokovic, playing in the late night match, cruised to a 6-1 6-0 victory over Lukas Rosol.
Only Spain's David Ferrer, the men's third seed, had an easier time. He won in a walkover when Dmitry Tursunov pulled out.
Meantime, Bernard Tomic has ended his feud with Davis Cup captain Pat Rafter and said he would be available to play for Australia in next month's tie next month in Uzbekistan, reports said yesterday.
Last January Tomic said he wouldn't be available to play in the Davis Cup until at least a September World Group playoff, if Australia made it.
The 20-year-old's stance came after Rafter, with the backing of Tennis Australia, suspended Tomic from the first-round Asia-Oceania tie in Taiwan last month for a lack of professionalism.
But the world No.45 said at the Miami Masters he was now looking forward to returning to the Davis Cup fold.
"The Davis Cup is going to be held after this (Miami)," Tomic was quoted by Australian Associated Press on Saturday.
"We're going to train in Munich when everyone's done here and then play against Uzbekistan.
"It's not going to be a pretty place but I'm looking forward to it.
"We have got a good team now. I think we should win and Davis Cup is back on the roll for me and I'm going to try my heart out when it comes."
Tomic's return is a big boost for Australia, a 28-times Davis Cup-winning nation which hasn't featured in the 16-team World Group since 2007.
Tomic, Marinko Matosevic and former world number one Lleyton Hewitt will vie for singles positions for the April 5-7 tie in Namangan.
