MELBOURNE, Australia -- There was mystery underfoot at this year's Australian Open.
The tournament was dotted with high-profile leg injuries, and the women's event in particular was defined by them. On Rod Laver Arena, Serena Williams rolled her ankle in the first round, Victoria Azarenka tweaked her knee in the semifinals and Li Na twisted her ankle -- twice -- in the final.
There was also a cruel turn of events on the men's side, with Brian Baker leaving the court in a wheelchair and having to undergo yet another surgery after injuring his knee on an outside court.
Back in the stadium, Novak Djokovic was slipping and sliding during the first set in both his fourth-round match against Stanislas Wawrinka and the final against Andy Murray, and Jo-Wilfried Tsonga looked like he was having similar problems during parts of his quarterfinal against Roger Federer.
Murray said a "misstep" returning a Federer serve in the semifinals led to a strained hamstring, though since he did not identify the incident, it's not clear if that was a stumble or just a lunge.
Was it all a coincidence or a pattern? Probably a mixture.
Officials are adamant the court surface is not to blame. "The players will tell you right away if it's the court," said tournament director Craig Tiley. "They'll know it's the court, not me or anyone else watching. But we've received positive feedback.
"Not one player has complained about it. No medical staff have complained about it."
That seems to be supported by opinion around the grounds, and though official figures were unavailable, Tiley said the overall injury count was down this year.
The Australian Open used to be infamous for these types of injuries when the tournament was played on Rebound Ace from 1988 to 2008. The rubberized surface grew sticky in the extreme heat common during the event, and players' shoes would get caught, leading to twisted ankles.
"Since we moved from Rebound Ace to this surface, there's been an 80 percent decrease in ankle and foot injuries, and I think compared to tournaments around the world we're probably the lowest," said Tiley.
Strangely, the injuries suffered by Williams, Azarenka, Li and Baker all seemed to be the result of a "stick" rather than a slip.
The Plexicushion court used these days at the Australian Open is specifically prepared to improve traction behind the baseline, and there has been no change in the makeup of the court during the past few years. The area inside the lines, where the ball usually lands, is smoother than the grittier area outside the lines. That's where the players do most of their running these days. "It is actually quite a rough surface out there on the blue part on the back of the court," Lleyton Hewitt said while doing commentary for Channel Seven during the tournament.
"If you run your hand across the court, the inside of the court and the outside of the court, you'll feel it's a different texture," said Tiley. "And the reason it's a different texture is because we deliberately -- we've been doing it the last few years -- have a different kind of sand in the playing area and in the outside area.
"The sand is more circular in the playing area and more angular in the outside area. So it helps with the footing in the outside area but then it helps with the ball bounce in the playing area."
"But," he added, "The court's not specifically designed to grip. If you design the court to grip, your feet are going to stop and you're going to have the problems."
There has been one change to the way the courts were prepared, and it's the reason why the players have reported the courts are playing faster this year. The annual resurfacing of the courts took place about two or three weeks earlier, meaning that they were fully seasoned by the time the tournament began.
The meticulous testing done by the tournament indicates that a newly painted court speeds up over the first six to seven weeks and then levels off after eight weeks.
Moving up the resurfacing date was done to increase consistency. "This year, all the courts were resurfaced a little earlier than they had been before, so by the time the event started they were at their plateau, whereas before they were still increasing in speed during the event," said Tiley. "So when we started the event this year, we were at the same speed that we finished the event last year."
A hot summer also sped up the process. Tiley estimates the courts were about 10 percent faster at the start, edging from a medium-fast SPR rating of 35-38 to 37-40, which is close to the "fast" category.
Li's coach, Carlos Rodriguez, felt the footing problems could be related to this increase.
"The court is a little bit faster," he said after the semifinals, probably not suspecting that he would watch his player twice turn her ankle during the final. "For me, I think the problem is that the players have to move much faster. This stop and go. ... I don't think they're used to this. [Most] courts during the year is slower than this one. Even Sydney [the tournament the week before] is slower than this.
"And the players in my opinion slide a little bit too much," he added.
Rodriguez was referring to the relatively new phenomenon of players sliding into their shots on hard courts, a technique once reserved for clay courts.
"These guys move completely different to the old-style player," said ESPN analyst Darren Cahill. "They're sliding on the hard courts, which hasn't been done before; they're on the side of their shoes, not the flat of their shoes. And these guys are pushing themselves physically to levels, which we haven't seen before, so the stresses on players' shoes these days is a little more than it used to be."
Djokovic is a prime example, though his frequent slips early on against Wawrinka were eventually blamed on new shoes that were not sufficiently broken in. Rather than catching his feet on the surface, he simply wasn't getting enough of a grip.
"That's why it was at the beginning very slippery," said Djokovic's coach, Marian Vajda. "He walked in the shoes, but maybe not enough. Maybe he didn't slide enough before.
''And he did exchange them [for an older pair], and the contact was much stickier.''
The interaction between the court, footwear and footwork, especially in the rapid action of a match, means that a player's movement balances on a fine edge. Whether too sticky to too slippery, the surface or the soles, it wasn't always easy for players to find their feet during the past two weeks.