What can we take away from our time in Toronto and Cincinnati? From my perspective, the last two weeks subtly but perceptibly deepened, entrenched, normalized, the changing of the ATP guard that began with Rafael Nadal’s win over Roger Federer in the Wimbledon final. The sport has always taken its cues from what happens in its capital, the All England Club, and it was true again in the far-flung outposts of Canada and Cincy. There, Nadal consolidated his stirring victory on Centre Court by finally overtaking Federer at No. 1 after three years of toiling in the second spot. Just down the totem pole, two fellow members of the “young gun” generation, Andy Murray and Novak Djokovic, made significant statements—Djokovic by ending Nadal’s 32-match win streak and putting himself back in the mix for the Olympics and the U.S. Open, and Murray by winning his first Masters title.

Just as significant were the Top 10 players who didn’t appear in the later rounds at either event: Federer, who will be 27 next week; Andy Roddick, 26 at the end of August; Nikolay Davydenko, 27; and James Blake, 28. Tennis “generations” are pretty brief, lasting only about three or four years—in Toronto we were already talking about an even newer face in 19-year-old Marin Cilic of Croatia, who recorded the biggest win of his young career by defeating Roddick. But if this was not a full-blown coup by the young guns, it was the beginnings of a quiet revolt. Most significant to me was how natural it suddenly seemed that Murray and Djokovic would be the last ones standing at a Masters tournament.

We knew Djokovic belonged there, but while it was Murray’s first Masters final, it was also hardly a surprise after the improvement—in his play and, more important, his demeanor—he showed at Wimbledon and last week in Toronto. There he notched his first career win over Djokovic after three humiliating defeats. By the time the two 21-year-olds began their match in Cincy, the turnaround was complete. You might say that they switched their normal roles on Sunday: Djokovic was negative and volatile, while Murray was poised and able to channel his eclectic game into a simple, winning formula.

Djokovic had been scintillating the night before in beating Nadal. But there had been something a little too flashy about the way he went about it. The down-the-line forehand winners he kept firing past the Spaniard from outside of the court were not shots that anyone, including Djokovic, can keep hitting on a regular basis—as someone once said of the way Jimmy Connors hit backhand winners, the Serb seemed to think his shots were worth two points each. By the middle of the second set the next day, Djokovic had traveled 180 degrees in the other direction. As in Toronto, he couldn’t keep two consecutive forehands in the court against Murray. He spent the rest of the set fighting himself, his racquet, and even his normally trusty backhand, which he began to spray almost in imitation of his forehand. Only his serve allowed him to remain anywhere near Murray.

Part of this was physical. Djokovic was breathing hard early in the match and looked exhausted by the end. But I don’t think that was the decisive factor. I’ve said in the past that he carries a dangerous amount of frustration with him during his matches—think of it as a debt load that, on occasion, he can’t pay off. On Sunday ESPN’s Darren Cahill took this observation one step further. He noted during the second set that Djokovic had let his frustration overwhelm him to the point where he had checked out competitively and conceded that it wasn’t his day. I’d never thought of it quite that way, but it’s a trend with the Serb when things aren’t going well. The dissatisfaction gets to be too much, and he pulls a mental trigger. Sometimes he calls it a day completely (see his match against Federer in Monte Carlo), sometimes he chucks in his now obligatory drop shot when he’s down match point. Djokovic did that again on Sunday, except that the ball skimmed the tape and ended up winning him the point and eventually the game. That’s how the entire second set went for Djokovic; as Cahill noted, the more the Serb conceded, the more relaxed his shots became, and the better he played. Djokovic saved four match points at 3-5 and extended the final tiebreaker all the way to 7-5. Looking desperate to lose the set most of the time, he very nearly ended up winning it.

This is a different version of the Djokovic that I was writing about as recently as May. Regarding his recently-erratic forehand, maybe it’s Murray’s defensive speed that forces him to try for too much, or maybe that little flourish at the top of his backswing really does hurt its consistency. Djokovic can hit flashy winners from that side, but now we know that it can go off and bring down his entire game. More important was his mental approach to Sunday’s final. This wasn’t the same guy who was so uncannily confident, organized, and psychologically uncluttered at the U.S. and Australian Opens. What’s changed? I’d chalk it up to the expectations game. At those events, Djokovic was still the hunter; he had encountered almost no resistance on his shockingly smooth ride up to No. 3 in the world and a Grand Slam title. But that ended when he couldn’t pass Nadal this spring; since then he’s had to deal with defending his own position rather than hunting anyone down. He hasn't been quite the same player, first at Wimbledon and now against Murray. Maybe this is the downside of having such innate and uncanny confidence. When Djokovic’s game doesn’t match his own very high expectations for it, he reacts with an unsustainable and unproductive frustration.

Does this sound like someone we know? Until Wimbledon this year, “unsustainable and unproductive frustration” seemed to be the basis for Andy Murray’s game. But his victories at the All England Club proved once and for all to him that putting childish things away—including his distinctly adolescent rage—really did help. He had more evidence for that on Sunday, as he kept his temper in check all afternoon. But beyond that, Murray also showed a new maturity from a tactical point of view. His downfall in the past had been his entertaining but ultimately misguided passion for variety and degree of difficulty. Murray never hit two serves in a row the same way or at the same speed; when he put himself in a winning position in a rally, he tended to use his drop shot as a putaway (tellingly, it was Djokovic, rather than Murray, who was doing this in Cincy); and he seemed to go out of his way to get himself into scrambling defensive positions, just so he could try for a spectacular forehand on the run. As his ex-coach Brad Gilbert said yesterday, Murray was constantly changing his “playing philosophy” in the middle of matches.

Instead, he beat Djokovic by going against all his tendencies and sticking to one simple, disciplined philosophy: Keep the ball up the middle until an opportunity presented itself, and then work the ball outward from there. It’s baseline tennis 101, and it was the best way to beat Djokovic, who looked like he would have had trouble hitting the broad side of a barn at times.

Still, there were echoes of Murray's past. Despite outplaying his opponent for the entire first set, he couldn’t capitalize on any break chances. Up 6-1 in the breaker, he squandered a few points before Djokovic finally handed it back to him. Then, serving for the match at 5-3 in the second set, Murray double-faulted twice and retreated into his old defensive stance when he had match points. Up 4-2 in the second-set breaker, three points from the title, he made two bad errors and let out some vintage teeth-baring vitriol.

That’s when the new Murray reasserted himself, just the way Djokovic has on many other days. The two produced the best point of the match, a back-and-forth, corner-to-corner slugfest that Murray finally won with an aggressive, but not too aggressive, backhand crosscourt winner. It was the shot of a born tennis player, smooth, instinctive, and easily powerful. But it couldn’t have happened it Murray hadn’t channeled his frustration in a positive direction. All that was left was for him to stagger forward and hit a final backhand winner before collapsing into his seat on the sidelines, a Masters winner. As the ever-argumentative Chris Fowler of ESPN said of the budding rivalry between these two, "Who's the pigeon now?"

Together, Djokovic and Murray represent the latest form of the modern baseline game. Rather than building their games on killer serves or forehands the way Federer, Roddick, Blake, and Fernando Gonzalez did, they win with all-around efficiency and rely on their two-handed backhands as consistent weapons—their tennis is stylishly compact and made for all surfaces. But they’re also flip sides of that same modern coin, and they have the makings of an intriguing rivalry. Djokovic seems to be almost a computer-generated tennis player, with the perfect frame and an ideal blend of contemporary and classic technique. He arrived on the pro scene with his game fully formed, and is only now having to struggle with a little with the expectations he has created. Murray seems at first glance to be the consummate non-athlete—how many pro tennis players have wild red hair and look like they're hobbling around the court between points? Emotionally, he has also been a more typical kid than Djokovic. Murray has gone through a public growing-up process to get to where he is now, trying on a variety of coaches, attitudes, and facial-hair styles. But as of right now, these two young guns who were born seven days apart have arrived at pretty much the same place. Djokovic is No. 3; Murray is now No. 6, his highest ranking yet. It will be fun to watch them exploit their individual talents, and learn to deal with their individual frustrations, in the future. It will also be fun to watch them deal with facing each other. But that's the future. For today, with Murray's arrival and Nadal's ascent to No. 1, the ATP's new guard feels just a little more entrenched, a little more normal.