Top seed Novak Djokovic failed to get to grips with the controversial blue clay of the Madrid Masters but still survived a struggle to reach the third round 6-2, 2-6, 6-3 over Daniel Gimeno-Traver on Tuesday.
World number one Djokovic, originally cautious in his comments about the experimental surface which has drawn fire but little praise so far from players, was unable to stay in check after playing his match.
"It's impossible to move. I hit maybe five balls, the rest went just trying to put the ball into the court. I was relying on serve and getting free points from his unforced errors.
"That was not tennis, either I need football shoes or some advice on how to play on this court.
"I cannot find the words to describe this court. It's really tough to play like this on a centre court. We cannot change anything this year, but my first impressions are not good. I don't want to be the one complaining, but I say honestly what I feel.
"We need serious discussion about the future of this blue clay."
The Serb is playing for the first time since losing the Monte Carlo final to Rafael Nadal, the second seed here who has so far led the criticism against the blue look.
Djokovic beat the Spaniard for the Madrid title a year ago, backing up that win with another for the trophy in Rome.
Djokovic advanced after a struggle from seven aces and 20 winners after losing the second set on a double-break against the number 137 ranked Spaniard.
Czech sixth seed Tomas Berdych advanced over South African Kevin Anderson 6-4, 6-3, paving the way for a trio of French seeds.
Number nine Gilles Simon beat Fabio Fognini 6-7 (1/7), 6-3, 6-3 after playing his last match eight days ago in the Bucharest final against the Italian.
But Simon was scathing about the blue clay.
''I see no difference from last year, these have always been the worst court of the clay season. I could have sprained something practising," complained the Frenchman.
"There are other priorities ahead of making it blue - it should be better."
Gael Monfils, the number 12, returned after six weeks out with an abdominal injury and put out German Philipp Kohlschreiber 7-5, 6-7 (2/7), 6-3.
Estoril finalist Richard Gasquet won a marathon in two and three-quarter hours against Thomaz Bellucci 4-6, 6-4, 7-6 (7/5).
Estoril champion Juan Martin del Potro eased past Florian Mayer 6-4, 6-2.
The two leading women both reached the third round, with top seed Victoria Azarenka made to struggle by Czech Andrea Hlavackova before emerging 6-3, 7-6 (7/2) winner.
The Belarus player was serving for a quick straight-set result but was broken as her opponent pulled level at 5-5 in the second set.
The seed had to save a set point in the 12th game to bring on a tie-breaker, which finally saw her through with 32 winners in one and three-quarter hours.
"The surface is a bit slippery, but it's the same for all of us," she said of the blue clay court surface.
"I don't like to complain - it is what it is and it won't change now."
Second seed Maria Sharapova defeated another Czech in Klara Zakopalova 6-4, 6-3, firing 18 winners and breaking five times.
The Russian, whose match was started before 11:00 am (0900 GMT) due to the demands of television, said that a few days of training on the blue clay surface last week paid dividends.
"It's not so much about the colour. It does look good on television. But it plays a bit different. It's about the amount of clay on the court and the way it bounces," she said.
"You have to get used to it but I came here after winning Stuttgart and got in four or five days on it. I got settled in so it's just a matter of adjusting. It's also the same for everyone."
Number 13 Ana Ivanovic defeated Nadia Petrova 7-5, 6-1.