It wasn't the best week for a couple of the game's brightest stars. Our tennis aficionados weigh in on the latest from around the globe.
Rafa getting desperate
Carl Bialik, FiveThirtyEight.com: It's getting less surprising each time. Rafael Nadal lost again on clay, this time in Barcelona. He now has three losses on his favorite surface this year, equaling his total for last year that was his highest in a decade. And the struggling Spaniard has three more clay tournaments to play this spring.
Those could result in three more clay titles for the best player ever on the surface -- or, given how poorly he has played lately and the high level of No. 1 Novak Djokovic, three more clay losses. Djokovic has posed a threat to Nadal on all surfaces since 2011. What's different this year is that Nadal looks vulnerable against a whole lot more players. Fabio Fognini has beaten him twice, and David Ferrer, Pablo Cuevas and John Isner each have taken a set from Nadal. Suddenly, several other top players, who haven't yet recently faced Nadal on clay, may like their chances.
Barring injury, Nadal likely will be favored against anyone but Djokovic when he seeks his 10th French Open title. But with an unusually low seed number next to his name and lots of new challengers, Nadal could have much tougher matches than he's accustomed to.
Radwanska, Navratilova split
Peter Bodo, ESPN.com: If the partnership between Agnieszka Radwanska and Martina Navratilova taught us anything, it's that having a "supercoach" doesn't necessarily translate to super success. It's a sobering realization, considering the results put up by Novak Djokovic, Marin Cilic, Kei Nishikori and, of course, the player whose woes created the entire supercoach industry, Andy Murray.
This is only "news" in the most technical sense. Upon hearing that Radwanska had hired Navratilova late last year, who among us smacked his or her head and exclaimed: "Of course! It's a match made in heaven!"?
Granted, Radwanska might have been working under the impression that Navratilova would enable her to find that extra smidgen of toughness and determination that would transform Radwanska, a former Wimbledon finalist, into a Grand Slam champion. That certainly seemed to be a major contribution Ivan Lendl made to Murray's cause.
But Navratilova is a different, far more complicated breed of cat -- one far less suited to assuming the role of a plain and simple tennis coach. It would take a lot more space than we have here to really delve into that, but for now let's put it this way: When Lendl and Murray struck up their partnerships, you could compare their personalities and games and find some commonality.
That simply wasn't the case with Radwanska and Navratilova, as Radwanska's dismal results this year (12-8 in tournament play, no titles) amply demonstrate. Simple greatness, it turns out, is not communicable.
Estrella the late bloomer
Gustavo Goitía, ESPN Deportes: At 34, an age that for most tennis players means retirement plans, Dominican Victor Estrella is at his prime. This week in Barcelona, he achieved his first victory against a top-10 player, reigning US Open champion Marin Cilic of Croatia. A week earlier, in Monte Carlo, he had scored his first win at a Masters 1000 event.
Estrella is enjoying it as if he were a teenager taking his first steps in the ATP Tour and is far from satisfied: "The goal is to make it into the top 30 before the next US Open."
Together with Pablo Cuevas of Uruguay (champion in Sao Paulo), Estrella is one of only two Latin Americans with a title this season. With a victory in Quito -- Estrella's one and only career final -- plus a consistent run of results, he already has more victories in 2015 (10) than his previous personal best (nine in 2014). Estrella has also achieved his best ranking at 48th.
Tennis has no tradition in the Dominican Republic, a trademark factory of baseball players, but Estrella is leaving his mark by showing that through hard work, perseverance and professionalism, it is never too late to pursue a dream. And he is ready to go for more.
Murray seeking coaching stability
Alex Perry, ESPN UK: Andy Murray begins his clay-court season at the BMW Open this week with his coaching team plans up in the air.
The British No.1's full-time coach, Amelie Mauresmo, announced her pregnancy earlier this week, and Swede Jonas Bjorkman's trial basis looks set to move swiftly into a more regular -- possibly long-term -- role.
"If all goes well, he'll spend a lot of time with me through Wimbledon and after into the US Open as well," Murray said.
"He's a very calm guy. He's not in your face, but when he talks you listen. Sometimes, if someone talks all the time, you don't listen to most of the stuff. He's got a very nice way about him. He's easy going, but obviously he was mentally very strong and had a great work ethic as well, so hopefully that can rub off on me and the team as well.
"I'm going to spend the hard-court stretch to the end of the US Open with Jonas, then I'll see what happens with Amelie because I don't think she knows what her priorities are going to be and how she wants to deal with things, so we'll just see for a few months."
Murray has a bye in the first round of the Munich event as he begins preparation for the French Open -- the only Grand Slam in which he is yet to reach the final.
Federer headlines inaugural Istanbul Open
Matt Wilansky, ESPN.com: It's a good week to watch some old standbys take their games to new turf. Leading the way is Roger Federer, who will lead the field at the inaugural Istanbul Open -- the first time Turkey has hosted a men's event. The venue will be played at the Garanti Koza Arena, which, according to the ATP World Tour, is the "largest tennis academy in the world" and one that "features a retractable roof."
Federer will try and rebound from a disappointing Monte Carlo Open, where he lost in the third round. A nice showing would likely give him needed confidence heading into the apex of the clay season, Madrid and Rome. Grigor Dimitrov is the second seed.
Also on the calendar this week is the Estoril Open, which replaces the Portugal Open, a tournament that couldn't sustain the requisite funding to keep it going. Unlike Turkey, Portugal has been a staple on the ATP Tour. Feliciano Lopez and Nick Kyrgios will headline the stars there.