Rough day for the kids in Melbourne

Australian Open: Madison Keys, Heather Watson: Young stars get rough lesson, lose on Day 5 in Melbourne.

Two of the rising young stars who are destined to shape the future of women’s tennis tested themselves against members of the current hierarchy in the third round of the Australian Open on Friday — and quickly realized they had more to learn.

American Madison Keys, all of 17 years of age, showed plenty of potential but went down 6-2, 7-5 to fifth-seeded Angelique Kerber of Germany, who was celebrating her 25th birthday. Meanwhile, Britain’s 20-year-old Heather Watson lost 6-3, 6-1 to perhaps the hottest player in the world, No. 4 Agnieszka Radwanska of Poland, now 12-0 on the season.

Keys has grown into a formidable young athlete from the little 13-year-old I used to watch being put through her paces by John Evert at the Evert Academy in Florida. There seems little doubt that she has the tools to make quick strides up the ranking list from her current position of 105.

Just like Laura Robson the previous evening, Keys looked nervous in the daunting surroundings of the Rod Laver Arena. But, unlike Robson who fought back to beat Petra Kvitova, Keys found Kerber too relentlessly solid to cause an upset.

There was a moment when Keys got unlucky as Kerber found herself down 0-30 when serving to stay in the second set at 4-5. The German drove a ball onto the sideline and, as Keys was in the act of sweeping it away for a clean forehand winner, it was called out.

Kerber challenged and Hawkeye showed the ball had nicked the line by a millimeter. The point was replayed and Madison netted a backhand. Without the call it would have been 0-40. From 15-30, Kerber was able to fight back and profit from a wasted opportunity when the American was perfectly placed for a pass up the line and netted.

“Inexperience — I made some dumb decisions out there,” said Keys, being a little harsh on herself. “I think I psyched myself out, thinking I should be playing better than I had to play. Going for too much. But she’s a great retriever and makes so few mistakes. ... She’s not No 5 in the world for nothing.”

Keys realized the nervous beginning was to be expected.

“The occasion; first on the center court against a top seed, yea, it took a while to settle down. Right now it kind of sucks, but I’m proud to be one of several Americans to have done well here. I’m proud of everyone.”

With five American women in the third round, the US has enjoyed its best showing at the Australian Open for several years with another teenager, Sloan Stephens, scheduled to play Robson for a spot in the final 16 on Saturday.

Like the Kerber/Keys match, Radwanska and Watson were forced to stop while the roof was closed over the second stadium, the Hisense Arena, as light rain and cooling winds swept away the Thursday heat. Proof that the closure of the roof can make a considerable impact on conditions became apparent when Key’s ground strokes were clocked at 4 mph faster when the match went indoor. In this instance, it came too late to offer much benefit to the American.

Radwanska went in to the match with a perfect record for 2013, having won WTA titles in Auckland and Sydney. But she admitted to being nervous at the start and the confident Watson began well, getting break-point opportunities as early as the third game.

“After that game when I didn’t convert it, it just slipped away a little bit,” Watson said. “Then in the first game of the second set I had chances again, and then there was a little break for rain.

“When I came back on court the games just flew by. I realize I have to work on mentally staying focused throughout without, you know, blinking, because I can’t let it pass me by.”

Radwanska, last year’s Wimbledon finalist, is starting to look like a major threat to those ranked above her. She plays a different game, not totally unlike the young Australian Bernard Tomic, using changes of pace and subtle variations to ruin an opponent’s rhythm.

“I must say I’m really playing good and everything is working,” Radwanska said. “Of course it’s going to get harder against seeded players. We’ll see.”