World No.1 Serena Williams was given a reasonable test in her first match at the Madrid Masters on Sunday against Kazakh qualifier Yulia Putintseva before the American eventually prevailed 7-6 (7/5), 6-1.
Putintseva had come through two rounds of qualifying and she seemed to handle the warm conditions better early on in an extremely tight first set.
Both women broke each other once and Putintseva managed to save another three break points to force the set into a tie-break.
However, the World No.88 finally crumbled at 5-4 in the tie-break as she fired long and Williams served out the set before taking control in the second, breaking four times to close out the match.
"I felt a little sluggish at the beginning, but happily I was able to win," the 15-time Grand Slam winner told a press conference afterwards.
"I know I will need to play better as each match goes on."
And Williams believes the warm conditions in the Spanish capital should be to her advantage as the tournament progresses.
"I have been training in Europe for a little more than a week, but long enough. I trained in Paris for a few days and then I came here.
"I think these clay courts are really good, they are a little bit quick which is really good for me and it's also a lot warmer here so overall its really good."
However, it wasn't such a good day for Serena's sister Venus as she was forced to pull out of the tournament with a back injury.
The World No. 21 had been due to open play on Sunday on the main showcourt against Spain's Anabel Medina Garrigues, but she pulled out before the match could get underway.
"I was desperate to play in the Madrid Open this year, but unfortunately due to the pain in my back I cannot compete," she said in a statement released by the tournament organisers.
"I will continue working hard to return as soon as possible."
World No.10 Caroline Wozniacki became the first big name to fall in matchplay as the former world number one was beaten in straight sets by Yaroslava Shvedova 6-2, 6-4.