McHale leads a trio of ambitious US teens.

FROM THE MERCURY INSURANCE OPEN IN SAN DIEGO – Thursday at the La Costa resort is going to be big day in the development of US women’s tennis. Not the largest one we have seen in the past couple of decades, maybe not even the most critical one in the past year, but it will certainly be worth paying attention to when teens CoCo Vandeweghe, Christina McHale and Sloane Stephens take the court in third round matches.

It is certainly the first time this year that three American teens have reached the third round of a WTA Premier level event and it would take a fair amount of digging to find out the last time that happened. All scored wins on Wednesday with McHale advancing when Alla Kudryavtseva retired down 6-2, 3-1, Vandeweghe playing sloppy but tough to overcome Olga Savchuk 6-7, 6-4, 6-3, and the enthusiastic Stephens knocking out the slumping world No. 20 Julia Goerges 6-3, 7-5.

McHale has been making fine progress all year, while fellow 19-year-old Vandeweghe has largely been running in place, and Stephens has been up and down. No analyst or coach of note will say that any of them are surefire top-20 players, but I would venture to say that in good health and with stable mindsets that they all have at least top 50 potential, which isn’t a figure that most US fans will get too excited about, but one that will put them in the WTA mix week in and week out for the next decade. McHale is already ranked No. 66 and is almost assured to crack the top 60 by next week so she’s a near lock. The athletic Vandeweghe is No. 102 and ambitious, and the also athletic and bold Stephens is No. 131. No other country at the tour’s sole WTA event this week can claim to have three teens in the round of 16, so at least on Thursday, the USTA will have something to crow about. In fact, McHale is the youngest member of the top 70 and Stephens is the youngest player in the top 135 and soon to be in the top 120. I am sure there are some folks out there who like the upside of the next highest ranked 18-year-old, No. 160 Caroline Garcia of France, more than Stephens, but consider this: the talented Garcia actually lost to Maria Sharapova at Roland Garros, while Stephens actually beat Georges in San Diego. That’s what some folks call “scoreboard” and winning matches – not just showing flashes of brilliance – still means a whole hell of a lot in pro tennis.

With that said, all three American youngsters will be underdogs on Thursday: McHale against the crafty Aga Radwanska, Stephens against Tamira Paszek and Vandeweghe against Sabine Lisicki. Radwanska and Lisicki are major steps up from the foes that McHale and Vandeweghe faced on Wednesday and Paszek has been playing very well of late and can crush the ball. Interestingly, all those players are around the ages of 20-21. All broke out fairly early, slid a bit due to variety of factors (although Radwanska has been fairly steady) and now are decent sized factors everywhere they go. The US teens cannot say that yet, but who is to say that one of them could not pull off an upset on Thursday and make a bigger name for herself and sometimes in the next two years, that they won’t be the favorites against another group of teens? I’m not ready to cast them off as a bound-to-be mediocre group yet.

If I was to pick one of them to get through I would have to go with McHale because she is patient, can grind and hopefully will be told not to try and hit through Radwanska quickly, who is very crafty but is still struggling in closing out matches. Stephens will have to be spot on the ball because Paszek can rock the yellow pill. San Diego’s CoCo will play the night match against the streaking Lisicki and unless the German has an off serving day its hard to see how the American is going break her more than twice — if that.

Outside of the US circles, there are also some potential bang up matches with Virginie Razzano playing Andrea Petkovic, Daniela Hantuchova against Jie Zheng, Shuai Peng against Sara Errani and Alberta Brianti against Ana Ivanovic, who said after she came back from 0-5 in the second set to beat Ayumi Morita 6-1 7-6 (5) that she is trying to stop chasing her service toss, but won’t catch bad tosses because she feels it is unsportsmanlike….Elena Vesnina has an injured hand and retired from the doubles with Sania Mirza. India’s top player told me that she’s playing straight through the US Open and that she and Vesnina are going to try very hard to qualify for the year-end WTA Championships AND despite reports in India that her husband, Pakistani cricketer Shoaib Malik, is now beating her in mini or regular tennis, thatss simply not the case. He’s been kidding her about the one when they played three points in mini tennis and he won two, but that was the extent of it. Fun stuff for the cross-border celebrity newlyweds. Mirza also says that she believes she played 161 matches between Birmingham of last year and this tournament, which may be a record. Recall that she played both the Asian and Commonwealth Games. I can’t even imagine after reading that anyone will ever say that she does not put a huge effort into her tennis…Maria Kirilenko also pulled out with an injury. My the ailments are starting to pile up. ..Speaking of players who are going to attempt to play through the US Open, count Melanie Oudin in. The struggling teenager is thinking that this time when she arrives in New York, the pressure will be less on her because she’s not defending quarterfinal points like she did in 2010. Here’s hoping she pulls herself out of her slump because she really is a terrific competitor when she’s confident.

Some of you have cracked me for not covering the men over the past 10 days but frankly, when I’m at WTA tournaments and have zero chance to watch the men or talk to the men, there is no reason for me to get deeply into issues and matches I do not have a good handle on. It’s a much better use of my energy and your reading time to focus on people I can actually talk to in person and matches I can see. After San Diego ends, I’ll laser in on the men in Montreal and Cincy. And I do promise to call and write up something on the newly turned pro Jack Sock in the next two days or so.

Washington does have some interesting players though and on Wednesday, Donald Young, Fernando Verdasco, Nikolay Davydenko, Mike Russell and Radek Stepanek scored wins.