NEW YORK -- It may be hard to remember now, but the full-time traveling coach is a relatively modern phenomenon in tennis. A few top players first started paying for that moral and tactical support on the road in the 1970s. The practice became common in the '80s, and entrenched in the '90s.
Historically, players have tended to hire one coach at a time, agreeing to become joined at the hip 10 months a year. In rare cases, those relationships endure for most of a career; more often, they have limited shelf lives.
The dynamic is shifting. For one thing, the ever more far-flung intercontinental lifestyle can be off-putting for all but the single and ultrahardy, leading to some shared duties among coaches. For another, players with enough income and drive are increasingly inclined to bring in a coach for a specific purpose. In a couple of recent examples, Roger Federer and Andy Murray hired Jose Higueras and Alex Corretja, respectively, to help refine their clay-court games.
Now one of Higueras' most ardent pupils, former top-10 player Todd Martin, has joined the entourage of Federer's young Serbian challenger Novak Djokovic. The two spent the week before the U.S. Open working together, and Martin sat in Djokovic's courtside box for his first-round win against Ivan Ljubicic, intently taking notes.
Djokovic, who will face Australian qualifier Carsten Ball in the second round Thursday, said he expects Martin to help make serve-and-volley a more potent part of his game. But both he and Martin indicated the main goal is simply to give Djokovic a contrasting yet complementary take from the counsel of his longtime coach, genial Slovakian ex-pro Marian Vajda.
"I think it's nice to hear different voices, and it's nice to have a secure enough relationship [with a primary coach] to be able to do that,'' said ESPN analyst Pam Shriver. "Over a long career, which is what you want, you have to be willing to tweak things.''
Djokovic, 22, has had a solid enough year to keep him firmly in the conversation about Grand Slam contenders, but has been spinning his wheels in some ways. He's 2-5 in tournament finals this season, winning the Dubai title over Spain's David Ferrer and defeating a little-known Polish player in the new event his family owns in his native Belgrade. Djokovic's runner-up finishes in Miami (to Murray), Monte Carlo (Rafael Nadal), Rome (Nadal), Halle (Tommy Haas) and Cincinnati (Federer), seemed to show he's hit a bit of a ceiling.
Perhaps just as importantly for Djokovic, who broke the Federer-Nadal stranglehold on Slams when he won the 2008 Australian Open, he has not advanced past the quarterfinals of a Grand Slam in 2009. He admitted this summer that losing an epic semifinal against Nadal in Madrid last May haunted him for weeks.
Martin, a two-time Grand Slam finalist ('94 Australian, '99 U.S. Open), is "somebody that has been on top of the men's tennis, and somebody that has a positive attitude and great experience,'' Djokovic told reporters. "He always looks for positives, and this is exactly what I need.''
Martin, 39, lives in Florida with his wife and two young sons and said he has no interest in traveling full-time after investing 15 years in the itinerant professional's life. His only previous foray into coaching was a stint with veteran American player Mardy Fish.
The two focused on general match preparation and on revamping Fish's forehand. Martin bowed out after two and a half years, saying at the time that "Mardy did everything I asked of him in certain ways and not in others.'' Martin told ESPN.com that the experience was positive overall, and he plans to apply much of what he learned in working with Djokovic. "It doesn't matter what you have to share unless you share the right dosage in the right way at the right time,'' he said.
Martin first took note of Djokovic when he was a junior. "The moment he was finished with his match, he was in a field next door, cooling down appropriately,'' Martin said. "I've never felt like a grand prognosticator of future success, but I saw more in his after that match than during. He was clearly an organized, efficient player with a grip on what he wanted and how to get there.''
That last statement could describe Martin himself -- although the tall, cerebral, unflappable Lansing, Mich., native would be the first to say that he made the most of modest talent, while he refers to Djokovic's not-yet-fully tapped potential as "extraordinary.'' A sharper, more vigilant transition game could further round out an already very complete talent, Martin said.
"Novak isn't inherently a superaggressive player,'' Martin said. "He has to learn to volley better, develop a feel for the net and have the mindset that coming into the court is an appropriate move for him and a necessary move to finish a point he's earned the right to finish.''
The Madrid semi against Nadal may have sapped Djokovic, but it also helped counter the impression that he sometimes lacks mental and physical stamina in big matches. Martin said he doesn't feel there's any need to target that specifically.
"I don't think it's anyone's place to state, about another person, what may limit them,'' Martin said. "It's unfair to say one thing is the issue. We're all works in progress. Some guys cramp a lot during the first half of their career, and then it stops without their ever having found a panacea. Players are constantly going through physical changes. Novak's only 22.''
Djokovic has called on outside counsel before, working on his net game with Australian doubles great Mark Woodforde during two stretches of the 2007 season. And Martin is positively predisposed to a co-coaching situation. During his playing days, he and coach Dean Goldfine periodically visited Higueras' academy to train, and "whenever Higueras was [at events], Dean and I would welcome his participation,'' Martin said.
ESPN analyst Brad Gilbert, whose coaching résumé includes stints with Murray and Andre Agassi, theorized that today's top players are probably more comfortable with having multiple influences because they already travel with substantial entourages including trainers, fitness coaches and agents.
Gilbert never had more than one coach when he played, nor did he ever coexist with another coach. "I think it could be tricky,'' he said. "Who has the final voice? Who makes the strategy calls? If I'm traveling full-time and dropping everything, making that commitment to take someone to the next level and sacrificing the time away from my family I don't think I could do it. But that's just me.''
Tennis may be moving toward an era of more specialized coaching, but Andy Roddick recently pointed out that trend will have its limits for one simple reason: The player foots the bills, as opposed to a baseball team that carries a batting coach or an NBA team employing a free throw guru.
"If you're looking at making six figures a year, you're going to have to be in the top 80 as a tennis player,'' Roddick said. "You have to be making some bank in order to take on those expenses. We pay for all of our own stuff.''
Yet if Martin is able to help Djokovic bridge the last increment between himself and the men above him in the rankings, his input might be priceless.
Bonnie D. Ford covers tennis and Olympic sports for ESPN.com. She can be reached at email@example.com.